Watching Indiana Jones movies for some time got me wondering how you can effectively kill the explorers to your temple after a long time.

How can I prevent explorers from stealing my artifacts for at least 500 years?

Setup: I have about one billion dollars to spend and 50 years to build an "artifact temple". I can (and will) use 2015 technology - and anything that is accessible to, or can plausibly be invented by, an "Average Joe" in next 50 years.

For story purposes, I am planning a huge apocalypse in 50 years and civilisation declines to "dark ages" for at least 200 years. Then society will get back to today's tech (2015 level) in another 200 - 300 years.

So, my temple will be visited in year 2515 by archeologists to see what artifacts I hid there. And spoiler alert: I would like to get such archeologists killed.

How can I achieve that?

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    $\begingroup$ Does there have to be a 'right way' to go through the temple, or does just anyone die when they go in? And is there a theoretical limit to the body count? For instance, if a hundred guys fall into your spike pit, the next guy might just be able to walk over their corpses to the other side. $\endgroup$ Oct 29, 2015 at 13:57
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    $\begingroup$ There should be "right" way through the temple. And for the second, there is theoretical limit. I did nopt think about "100 people on spike traps" so I dont have any limit in head now $\endgroup$ Oct 29, 2015 at 14:12
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    $\begingroup$ Make the sliding door slowly slide upwards to close instead of downwards! $\endgroup$ Oct 29, 2015 at 20:20
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    $\begingroup$ Reading a lot of the answers, my response would be "is there any reason why Indiana Jones at the 2015 level of technology wouldn't use probes"? Even if we're not talking full-blown robots, at the very least some careful application of sensors would avoid boring stuff like "just irradiate the area" or "make the area unbreathable". If I encounter a hermetically sealed door, my first instinct would be to breach it very, very carefully, not just for my protection, but also that of the purported treasure within (which may not take kindly to a sudden inrush of air). $\endgroup$ Oct 31, 2015 at 1:40
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    $\begingroup$ A large amount of effort has been put into the question, "how do we discourage people from looking in this site for thousands of years?" at the (nuclear) "Waste Isolation Pilot Plant" : wipp.energy.gov/picsprog/articles/… $\endgroup$
    – pjc50
    Nov 2, 2015 at 11:58

23 Answers 23


Plastic, plastic, plastic.

Metals will rust, organic materials will be consumed by mold and other fungi, but plastic lasts forever.

The Temple

Start out in a preferably warm, dry climate. However, avoid sandy climates or deserts, where sand and wind will become a problem over time. The West Coast of the U.S. strikes me as a decent location, as long as you stick to the Valley. Protection from salt water, high winds, and below sea level, as well as being dry and warm year round. (Smack dab in L.A. seems like a great place to build a Temple to the Ancients, in my opinion.)

Then, build a structure that brings to mind ancient buildings, built with concrete. It's been proven that our modern concrete is just as strong if not stronger than ancient concrete. It is merely aspects such as plumbing, wiring, and other factors that cause our buildings to be less sturdy.

Ideally, you will want to build something along the lines of the ancient pyramids, but made with modern hardened concrete. This structure is massive, and therefore will resist erosion. Within the pyramid you will have many small rooms, which will give the pyramid stability. A pyramid shape is good because it has a wide base with less weight as you go up, but you could just as easily create a giant box as well. The idea is that you make sure it is sturdy, with as few seams in the concrete as possible. Pouring the walls as one solid piece will be the best way to ensure no moisture can infiltrate the cracks and begin to break apart the concrete pieces.

In order to attract the adventurers of the future, lets say we want to build something pretty damn big. So, 100 feet tall (10 stories), and 50 feet wide. This creates a very tall but narrow pyramid, so adjust your width accordingly for something fatter. This puts our surface area at 12,807.76 feet (I used this calculator to figure this out, I'm not a math person).

If we use this number on building a concrete home, take the high end - 3.25 US dollars per square foot - and then add on an extra 2 dollars for more expensive and solid slab concrete (with no space within for plumbing and wiring), then we're looking at a cost of 67,240.74 dollars, a tiny number compared to your budget. (If someone else who isn't math stupid finds out that I'm crazy wrong, please let me know.)

Inside the Temple

The interior of the pyramid should be sealed from moisture, perhaps with a coating or sealant or non-biodegradable foam. Vulcanized rubber would be a good material as well, especially to make sure your doors are hermetically sealed from your adventurer until the time is right. Removing the oxygen before sealing would be a good way to initially try and cause some damage, merely opening your temple would cause the door to blow open, and the adventurer would have to wait for the temple to be filled with air before he could venture inside.

Creating a complex system of hallways and tunnels will ensure that even if your adventurer gets past your booby traps he (or she) have a strong possibility to get lost. Perhaps mechanical devices that seal doors once triggered, or which rotate a room or hallway so that it no longer points in the same direction it once did. Slops so slant that you can barely tell you're going up (or down) or rooms tilted at odd angles will leave your adventurers bewildered. (Magnets placed within the walls would prevent someone from using a compass accurately, and thick walls would keep someone from attempting to use a GPS device to position themselves). Confusion would result in an inability to map the interior of the temple, leaving adventurers to starve and die within the myriad of tunnels.

Booby Traps

All the traps should be extremely simple mechanical traps. Think something Rube Goldberg-esque. Opening a door triggers the release of a heavy ceiling covered in blades, sending it crashing down on an adventurers head.

Levers, pulleys, counterweights and other simple mechanical devices will be your friend.

All of the traps should be made of plastic or ceramics. Ceramics can be sharpened to a point for spike traps, for example, and will add some weight to things that need to squish someone. Plastics also have the benefit of being cheaper. You may be able to 3D print all the materials needed. This guy talks about perpetual motion machines and other mechanical devices that can be created with 3D printing.

It should be important to note that once a trap is triggered it would be impossible to set it back up, so this is why the confusion angle might be a better way to keep adventurers out. The first dozen people will end up triggering the traps and the 20th guy will be able to waltz right through. Unless you make it so he gets lost. Then your adventurers will eventually just have to trial and error, and hope they brought enough supplies to make it to the end. And even once they get there, they may not be able to get out.

Another good way to try and kill your adventurer would be with significant amounts of radioactive material. Uranium is going to last 4.6 billion years so I am pretty sure that qualifies. This would be a great way to create a temple with a "curse" attached to it. Within a few days or weeks anyone who enters and explores the temple would die of radiation poisoning.

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    $\begingroup$ I think you nailed it with radioactive material. Honestly, it's all you need. $\endgroup$
    – Samuel
    Oct 29, 2015 at 16:42
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    $\begingroup$ @Samuel yeah but that takes the fun out of it. I want my adventurers to believe that all they have to fear are physical threats, not poison. Messes with their minds. $\endgroup$
    – C. VanHorn
    Oct 29, 2015 at 17:19
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    $\begingroup$ 50 feet wide isn't very big - you'd get around as much area as the average US house. That's not nearly enough space to have enough rooms to make it confusing. Also, for calculating how much concrete you need you should use volume rather than area. $\endgroup$
    – Rob Watts
    Oct 29, 2015 at 18:31
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    $\begingroup$ Plastic does not last forever and certainly not longer than metal. Think about medieval coins dug up or sunken ships found in the ocean where even the wood is preserved. The linked article is talking about complete degredation of plastic waste, it is not saying a plastic item stays in a usuable state or doesn't break down at all. $\endgroup$
    – JamesRyan
    Oct 30, 2015 at 14:59
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    $\begingroup$ "All the traps should be extremely simple mechanical traps. Think something Rube Goldberg-esque." What. $\endgroup$
    – geometrian
    Oct 31, 2015 at 20:26

Put the temple in medium earth orbit

This has many convenient effects for your goal of slaughtering an aspiring archaeologist:

  • You don't have to have as many layers of traps, because only a few explores will have the means to reach your temple in the first place
  • Traps that would be mildly inconvenient on earth are extremely deadly in space
  • if you are careful in material choices, you don't have to worry about decay/corrosion at all.

Adding a big reflective balloon to your temple will make sure that everyone remembers that its there, and 500 years of stories about "the fastest star" will make sure people try pretty hard to get in.

Some traps suitable for space:

  • Spring loaded hollow needles for gently letting the air out of suits
  • Heat traps: spray your explorer with insulating foam and he'll cook in his own body heat
  • ruin the docked spaceship: when an inner door is opened, spray salt-water in all directions: good luck cleaning the salt off your engine bell in space!
  • space is a great insulator: use a radioactive beta cell to charge random elements of the temple to thousands of volts.
  • mercury is a great conductor: splash a liter of it onto a spacesuit and see what shorts out
  • have a room on the outside of the temple that uses solid rocket motors to fly away when someone enters it. Bye!
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    $\begingroup$ Space... Why'd it have to be space... $\endgroup$
    – Kasran
    Oct 30, 2015 at 15:32
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    $\begingroup$ Good luck trying to keep that within the budget $\endgroup$
    – Rob Watts
    Oct 30, 2015 at 17:42
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    $\begingroup$ Maybe what's so valuable is a cheap way to get to space in the first place. $\endgroup$
    – Joshua
    Oct 30, 2015 at 18:20
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    $\begingroup$ The OP specifies +50 years. With the progress SpaceX is making in reducing cost of space launches, this is a very plausible answer. $\endgroup$
    – March Ho
    Oct 31, 2015 at 13:56
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    $\begingroup$ This solution may also spur on the development of technology in 500 years, as the people try to get to your moon. Wait, that's no moon! $\endgroup$
    – dotancohen
    Nov 2, 2015 at 6:44

I am not really malicious enough to spend my time designing booby traps.

So instead I'll just present how a nice person such as myself would built a treasure vault for reference.

It should be filled with chemically inert gas for protection.

To avoid leaks the gas should be heavier than air and the vault built well below ground level in an are with very low ground level. A layer containing highly viscous fluid should be incorporated to make it self-sealing and add some elasticity to the overall structure. This makes cracks allowing protective gas escape less likely.

Since some gas would inevitably escape it should be self regenerating. As long as it is heavy enough to settle to the bottom and the vault only leaks from the top where the entrance to the surface is, any oxygen leaking in will be pushed out.

Chemically inert implies a noble gas. The heaviest noble gas is radon. Unfortunately radon-222 has a half life of less than four days before decaying into polonium-218. Which in turn decays into lead almost instantly. Covering my treasure with lead dust is not optimal.

Next option is xenon. It has eight stable isotopes. After quick inspection the most suitable is probably xenon-129.

Xenon has density over four times that of air so it should stay put in a hole. Xenon-129 is produced by beta decay of iodine-129, so you could make it regenerate. The half-life of iodine is long enough that the protective gas would regenerate for millions of years. Much longer than the vault would remain intact certainly. Beta radioactivity is also easily contained by placing your iodine inside a metallic container thus avoiding, together with the long half-life, embarrassing episodes with Geiger-meters going insane.

The only real downside to xenon that it is a powerful anaesthetic and since it is obviously unbreathable and concentrates near the floor people carelessly entering the vault would die. Fortunately xenon anaesthesia is fairly safe. So as long as you remember it is there and take proper precautions, no permanent ill effects to your employees are likely. In fact xenon is being used for doping, so your employees might even have increased performance from the inevitable low level xenon exposure.

Pity about the foolish explorers entering the vault unaware of the protective gas, though. Xenon is invisible and odourless and by the time concentration is high enough to snuff out flames, the poor explorers are probably already unconscious and suffocating. Nothing is perfect.

Since xenon is used medically and for other purposes on commercial level, it is easily available, if expensive.

Krypton is also a possibility.

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    $\begingroup$ As a plus, Krypton would also keep Superman out. Oh, wait... $\endgroup$ Oct 30, 2015 at 14:34
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    $\begingroup$ So a simple breathing apparatus (even a long tube) would be enough to defeat your trap. $\endgroup$
    – wjousts
    Oct 30, 2015 at 18:39
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    $\begingroup$ @wjousts Traps rarely work properly, if you know of them in advance and have the time to be careful. Whether the needed countermeasure is simple or complex affects simply the time it takes to defeat the trap. On a 500 year time scale there is no meaningful difference between "takes 5 seconds to counter" and "takes 5 years to counter", so the only criteria are being subtle and persistent. $\endgroup$ Oct 30, 2015 at 20:32
  • $\begingroup$ The real downside to using gas is that it's assumed. The air inside a 500 years old sealed chamber will be unbreathable anyway so either flushed out when you open the tomb or the people going in will use breathing apparatus. $\endgroup$
    – Separatrix
    Jun 4, 2016 at 7:34

Multiple answers have involved radioactivity. This will be quite problematic, though--alpha and beta emitters are completely harmless to someone wearing a simple full-body covering with a filtered air supply. The only threats are gamma and neutron--and such high energy decay is generally coupled with short half lives.

The only suitable isotope I'm finding is Americium-241 but you'll need a lot of it. A 100kg block at 1 meter administers a lethal dose in about an hour--but that block puts out 11,000 watts of heat. (And since you're looking for 500 years in the future you'll have to close to double the initial amount.)

Since you can't make him stand there long enough to fry you'll have to make him take a slow, winding path past vast amounts of it--and by then he's going to die of overheating long before he dies of radiation exposure.

If you want to use radiation as killing agent you're going to have to generate it when needed. Thus we need a radiation generator that can still work after 500 years. As others have said, stability is a big issue. A normal nuclear weapon contains a lot of pretty precise components that likely won't behave properly after the centuries. Besides, we just want to kill the archaeologists, not destroy everything.

Lets build a different sort of nuclear device. All the intricacy of a nuclear bomb comes from the desire to get the biggest boom--but suppose we don't want a boom? The idea of a nuclear bomb that doesn't go boom sounds crazy but it's exactly what we need here. Our material will be Pu-239 but we are going to build a gun-type bomb. (Yes, I know, you can't--read on.) The two chunks of material will be coated in something very non-reactive--teflon comes to mind but there might be other suitable choices.

Now, we also have the problem that we can't count on our explosives to behave after 500 years--thus we won't use any. We place one half of the bomb in the chamber we are trying to protect, likely hidden behind a thin panel. We place the other half of the bomb above in a pipe. There is something behind the other half that fits into the pipe to keep it aimed straight. Rather than a ring and cylinder we use slanted faces so that if it's every so slightly off after the centuries it still drops in place.

What happens when the upper half falls? The bomb assembles far too slowly, once it crosses the prompt critical threshold the reaction builds--and it produces heat. This energy quickly vaporizes the plutonium and it blows itself apart. We have seen events sort of like this due to mistakes in plutonium processing--the plutonium goes poof, the blast wave can knock down those who are close enough but that's about it--except they absorbed a huge radiation dose and quickly die of it.

Now, for the trigger. As others have said, it's not going to be easy to make something that will work reliably after the centuries so lets keep it simple. Put a door on the room. The door fits snugly in it's frame. There is a pipe in that frame, the pipe is full of beads of some kind--they are large enough they can't slip between the door and the frame. Once you open the door the beads drain out--and when the beads drain away they release whatever is holding the upper part of the bomb in place.

Edit: A second design comes to mind:

Forget about the two chunks of Pu-239. Instead, the beads themselves are the Pu-239. They're stored in a long, thin tube so they don't go critical while they are sitting there. The floor is sloped, it channels them to a collecting point where they do go critical.

  • $\begingroup$ ... Americium-241 ... 11,000 watts of heat ... I smell an unshielded RTG for resetting all the other traps, and anybody who makes it to the final room ... $\endgroup$
    – Joshua
    Oct 30, 2015 at 18:23
  • $\begingroup$ Wow I super like this answer. It has everything needed, it's unusual, and sounds very effective and unexpected. You won't have Future Indy looking at the floor to see triggers or guessing that the shaft of light is important. +1 $\endgroup$ Oct 30, 2015 at 20:05
  • $\begingroup$ The heat sounds more useful than the radioactivity. Add some insulation, and you can keep the entire complex heated to an unlivable level. Won't kill anyone smart, but will keep people out without interesting gear. $\endgroup$ Oct 30, 2015 at 21:27
  • $\begingroup$ @ToddWilcox What shaft of light are you talking about? What Future Indy sees is the beads spilling out when the door is opened. $\endgroup$ Oct 31, 2015 at 3:41
  • $\begingroup$ @user3757614 Yeah, it would be a fair deterrent (It's not easy to protect against such heat) but the objective was to kill him--and thus I consider the heat a problem. $\endgroup$ Oct 31, 2015 at 3:43

Simple use a Money Pit

I hear you asking ''What on Earth is a money pit? it sounds terrible for hiding things'' Well the money pit was a well like structure discovered in 1795 (We still are not sure how old it is) made of many layers of wood, clay and brick with small tunnels leading to the ocean. The pit is around 200 feet deep(estimated) but you could make it 500-100 feet deep and it should still work.


  • Over 1.5 million dollars have been put into digging into this hole and it still has not been breached
  • If almost 300 years of digging can't breach this pit then no one in the apocalypse will try. Why because it's the apocalypse and they have bigger problems
  • Consider that the actual pit was out in the open, if you buried it under a few feet of dirt who knows how long until it is found!
  • Whenever the tides rolls in the pit floods bringing in more clay and sand. The ingenious engineering of the tunnels make it so that water will flood the pit and prevent further digging
  • Since you need it to be lethal, borrowing from C Vanhorn's answer you could put uranium at certain points of the pit to make it lethal.
  • The original pit was built out of scavenged materials like logs, charcoal and coconut fiber (which is odd because coconuts don't grow here in Canada). Since you have 1 billion dollars you can use thick netting, cement, and titanium
  • To make it more lethal you can mix thermite with the fluid materials like clay to make it impossible(and dangerous) to use explosives. (Thermite is another cheap effective material)


  • It needs to be built near (within 100 meters) the coast.
  • This will not kill people (other than the occasion drowning), it just makes you go mad. I imagine that you could make it lethal though.

Utilize multiple passive traps around and within the temple. Defense in depth will ensure that even if some of your measures fail, the filthy archeologists will still snuff it. Use radiation, heavy metals, elemental explosives, and physical traps (like the Indiana Jones Temple of Doom).

Passive Means

Radiation is an excellent way to deny access to an area. Chernobyl won't be a habitable place for humans for 320 years. A highly prepared person with shielding and Geiger counters will be able to avoid harm but an unshielded person will die very quickly and very unpleasantly. Note that care will need to be taken to choose the right radioactive element to embed in the temple. Uranium isn't a good option because it's so stable over long time periods. Plutonium may be an option. The trick will be to get an active enough radiation decay that it will kill the intruder but last long enough to be lethal in 500 years.

As a trap, put up lead shielding around a room to prevent detection till the door is opened and the explorer gets a massive radiation dose right in the face. Go one step further and lace the area with super fine plutonium dust for a double-whammy of radiation poisoning plus heavy-metal poisoning. According to Wikipedia:

Plutonium is more dangerous when inhaled than when ingested. The risk of lung cancer increases once the total radiation dose equivalent of inhaled plutonium exceeds 400 mSv.

Elemental poisons also work well because they don't decay with time, provided they are stable in normal atmospheric conditions. Mixing a variety of super fine heavy metal powders with plutonium dust will cause all kinds of problems.

Elemental Explosives If you want more of a bang and don't mind a one shot trap, seal fluorine in an appropriate container that will shatter open. When the container shatters, the fluorine gas will be released into the air and hopefully the luckless explore will get a big lungful.

Unreliable Approaches

Forget electronics, since you can't be sure that in 500 years the electronics will work or that your power source is even still active.

Don't rely on active traps that rely on ropes, pulleys, joints, actuators, hydraulics or chains since you can't be sure that these components won't seize, rust, rot, corrode or fuse in the 500 years that they sit. Even having a big block that falls on someone is tricky to get right because what if the ground settles and the big block jams? Designing a release that can hold a large load but give way with light pressure (in the right place) is hard to do. Ensuring that it's 100% reliable in 500 years is much harder.

However, even if the active traps aren't 100% effective in 500 years, if you put enough of them into the temple, the law of large numbers means that at least a few of them will work.

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    $\begingroup$ "Chernobyl won't be a habitable place for 20,000 years" - false. Animals are living there now. $\endgroup$
    – Rob Watts
    Oct 29, 2015 at 19:28
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    $\begingroup$ @RobWatts true, it's only 320 years and we don't care whether the animals are irradiated, only humans. $\endgroup$
    – Green
    Oct 29, 2015 at 19:38
  • $\begingroup$ Loren Pechtel's answer explains why passive irradiation is not an effective means to deny access to an area for 500 years. $\endgroup$
    – March Ho
    Oct 31, 2015 at 14:08

Make it Big

If it's big any team ill need to split to cover more area. Also a nice way to make explorers to hopeless wander way and get lost and tired is to build a maze. A huge maze is a challenge by itself.

Make it Difficult

No torches or lights of any type. Muddy terrain is also a great way to slow down explorers. Also water to the kneels and darkness are invaluable to hidden traps and dangers.

Make it Hazard

To increase lethality you can put all kinds of hazards. @Loren answer put a good point in ruling radiation out. Also plutonium is expensive enough to expend all your budge and we want to kill that guy in the place, not from cancer years later.

The place can be natural habitat of nasty creatures. The list goes from poisonous jellyfish to crocodiles but small swarming indigenous pests are easier to maintain (unless you create a institution to feed and keep that gigantic pythons preserved).

Another good environment hazard are poisonous gases like sulfur. They are pretty common in some places too.

Flooded cave!

You are luck there already places on earth with all that traits and they exists despite human intervention. In fact cave diving is a very hazard occupation. There's very little margin for errors in that business.

They are huge dark mazes and if there's not too many poison to support life anything can live here. Sometimes thing's no outsider ever been saw.

Just build your temple in that god forgotten deepts and enjoy the killing.

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    $\begingroup$ And you can make your flooded cave even more dangerous with a few well places obstacles like nets to snag the unexpecting diver. $\endgroup$
    – wjousts
    Oct 30, 2015 at 19:07

Read "Cryponomicon" by Neal Stephenson. This includes a description of an underground flooded cave network designed to hold stolen Nazi treasure and kill unsuspecting treasure-hunters.

The basic premise was that a lake above would pressurise tunnels around the area. Anyone digging without knowing exactly where to go would be crushed by high-pressure water, which would then flood the tunnel system.

The second archaeologist would know what to expect and could figure out what to do about it. Solutions might involve backhoes or thousands of slaves, depending on the new civilisation, but the first mouse gets the trap.

Investment would only need to be a few million dollars and a year or two of digging.


Make multiple temples and use social engineering to kill the adventurers.

First hide your artifacts in a cave or some such and take pictures. Then seal off the cave. You can completely seal it with no known entry if you like, or anything, do not put any traps in this cave.

Next make many other caves, temples, etc. as you wish. All of them trapped, as you like, none of them with artifacts in them.

Lastly, make exciting treasure maps with copies of your picture of artifacts affixed to them that all lead to the deadly caves and temples. Do not make any map or provide any information on your actual stash.

Distribute your maps. With any luck, the treasures, maps, pictures, etc. will become legendary and will be copied and passed down to maintain interest for 500 years.

Since no one knows where the true cave is, it should be extremely difficult to just stumble upon. Everyone searching for your treasure will search your trapped temples, and find an untimely end.


There's been a lot of good ideas thrown around, there's also been ideas whose feasibility is questionable.

The main challenge we face really is those 500 years. A lot can happen in that time, from the collapse of known society (you do mention apocalypse) and natural disasters. As such, any too elaborate trick is likely to just collapse before the time is right.

Passive Traps

Let's place the above-ground temple above the most inhospitable place ever:

  • hot (above 50°)
  • underground (and narrow)
  • filled with salted water
  • and a few "lures": underground rooms with either neutral, poisonous or explosive gases

Just wandering in this environment, by itself, is hazardous enough to kill all but the most prepared adventurer. Underground waterways are perhaps the most dangerous places to visit to start with, a couple narrow passages being able to keep all but the most determined (and prepared) adventurer. Turning on the heat is also a very nasty trick, as the human body cannot easily support it, and how would you navigate narrow passages in diving + heat protecting gear? Also, if deep enough, there will also be pressure issues. Finally, the lures are just to get those exhausted adventurers who finally hope for relief out; a couple easy kills, if you wish.

Oh and the salt? Well, in such a dangerous environment, one might be tempted to send bots. Narrow passages are annoying to navigate for bots, the difficulty in communicating (wires can only be so long), also raise the bar... but for the truly motivated we'll also make the water the enemy. Anything that can deposit and accumulate itself on the surface of the equipment and require frequent maintenance is good; salt might work.

But that's just the setting...

Note: this is building on jean's idea, with the heat twist inspired by QuadmasterXLII's heat trap.


Since the environment in itself is so hazardous, a sure-fire way to kill adventurers is just to increase their exposure.

As a result, let's make that network of submerged narrow underground passages a twisty maze. A dark underground is already a formidable maze by itself, but picking from C Van Horn's answer, we can improve this maze:

  • make it massive: there are already existing large underground networks so it's just a matter of acquiring one (which really means acquiring the land above the entry)
  • make it deep: deep enough, and GPS are out of the equation; it also synergize well with mortality (by increasing the pressure)
  • make it magnetic: with magnets placed strategically, compasses should be just slightly off, and off in a direction you control
  • make it off: if there are any straight passages, make them slightly slanted (in any direction), if there are large passages fill them so they get slanted. Oh, and if you figure some material that will resist time, a few slightly erroneous partial maps on the walls here and there...
  • make it unrelenting: any big room could conceivably be exploited to build a base camp, fill them in (mostly) to prevent such camps as much as possible

What does this maze brings?

  • it prevents a run-and-grab strategy: if you don't know where to go, you can't run-and-grab
  • it increases the adventurers' exposure to the environment: the environment itself IS the enemy, by increasing exposure we increase the death toll


A couple booby traps here and there would only increase the mortality:

  • jagged rocks (or ceramics) would play havoc on diving gear
  • ...

There is no need to use anything electronic or mechanism, just push the nature a bit further.

Pulling it off

Ideally, the underground network should NOT be flooded in your lifetime, this gives you the opportunity to set it up as you wish, and actually use it.

Then, when the time is right, fill up the biggest rooms, put the gases and other traps, and flood the complex (with hot water from a nearby water table).


Put your artifact temple on an escape trajectory

If your incredibly valuable artifacts are reasonably light (a few tonnes, maybe), you can easily set up a spacecraft to send them. With a 500-year head start, your artifacts would be light-weeks away. Plus, you have centuries to line up near-perfect gravity assists.

Because of the Tyranny of the Rocket Equation, catching up with, slowing down, and returning to Earth, would be impossible with 2015 technology. Let alone in a reasonable amount of time. Indy will die of old age on the way.

  • $\begingroup$ If the temple cannot be reached, you cannot kill people with it. Making archaeologists die on Earth seems like a major cop-out, they won't even bother going there. $\endgroup$
    – March Ho
    Nov 1, 2015 at 0:19
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    $\begingroup$ @MarchHo The question, bolded and verbatim, was "How can I prevent explorers from stealing my artifacts for at least 500 years?". In any case, anyone who comes after the treasure will surely die before reaching it. That satisfies any alternate interpretation too. $\endgroup$
    – geometrian
    Nov 1, 2015 at 0:45
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    $\begingroup$ If you want the artifacts to be available at some point in the future, say 1000 years, put them in a comet type orbit with that period. They will come back, but not any time soon. $\endgroup$ Nov 2, 2015 at 10:36

Let's think outside the box, here... How about the free-market solution?

Hire guards

A billion dollars is a lot of money. Clever investments could be done to make it last through the dark ages, and compounding interest alone could be used to hire a squad of people on semi-permanent duty to defend your temple.

To make this work after your death, design your temple with a radio transmitter in it. If the doors are breached, the transmitter would transmit the signal to an outside source, that would immediately cut off the flow of wage money to any remaining guards. Thus this would incentivise guards to carry out their jobs well.

The advantage of guards is that they would also be expected to upgrade their technology (and any physical defenses) in accordance with any new discoveries or inventions. This would protect you against unpredictable events. Your 'secret order of the hidden temple' could work to hinder your archeologists long before they even find the temple.

This might be more fun for your story than just disarming traps, also.

  • 4
    $\begingroup$ (1) This is expecting electronics to work after 500 years, (2) this is expecting whatever bank is used to survive the apocalypse and last 500 years. It does not seem reliable. $\endgroup$ Oct 30, 2015 at 18:30
  • $\begingroup$ There is also the risk of the guards becoming Indy, by hacking the door trap so they can both gain access to the money as well as the loot inside the temple. $\endgroup$
    – March Ho
    Oct 31, 2015 at 14:12

Build temple. Seal temple. Start three proselytizing religions based on the belief that all other beliefs must be terminated with extreme prejudice. Ensure all three religions know that the temple contains the only worldly evidence of [insert deity here]. Can be shown to be effective for up at least 2000 years.

You see, 500 years is a long time for technology to work, buildings to not settle, leaks to not develop (allowing water to dissolve and sweep away your radioactives, nerge agents, chemical agents, and biological agents). Humans however, are known to create conservative social structures that last for thousands of years with (in some cases) very little mission drift.

Hubbard launched his version for much less than US$1B.

  • $\begingroup$ Hubbard has a temple of doom? $\endgroup$
    – JDługosz
    Oct 31, 2015 at 6:50
  • 1
    $\begingroup$ @JDługosz : All evidence points to a boat. $\endgroup$ Oct 31, 2015 at 6:51

Your temple is - a ship.

Add an explosive charge, then sail out to the Marianas Trench. Abandon ship, then trigger the explosive (ie. "scuttle" the ship).

Your temple is now in what I'd call the hardest place on Earth to reach.


A nice variant on the maze idea (because being lost is terrible for your head): make the halls much smaller ; no too small so that normal-size human can crawl, but not too big. The idea is to make the human go slow, very slow, so you have time to expose him to all kind of radiation, gas, and the best: basic, mechanical, unescapable traps. In Indy movies and the likes, the hero always gets to jump from a good slab to another, to avoid the dangerous ones. In a tight tunnel, there is no way to jump over. Not easy way to turn back when something dangerous comes fast your way, no way to avoid those sharp spikes coming from the ceiling, etc. A cool one is: walls closing in front and behind you, water flooding, and after a few hours, going away. In any case, vary your traps, so even the hardy adventurers won't know what to expect. Oh, and if Indy is claustrophobic, tough luck :)

As an additional benefit, the bodies or previous adventurers will soon fill up the tunnels, making any progression much harder.

Things you might want as extra protection: make sure radios signals don't get in, to avoid small robots to steal the show. You could even make a few guillotine on the way to cut through cables if that's what the bot uses to receive orders.

Obviously, nothing forces you to put your treasure in the last room. It could be under a few meters of concrete somewhere else.


Drill into the bedrock

Currently Sweden and Finland are planning to bury their radioactive waste in bedrock repositories, 500 meters below the surface.

Our method of final disposal

You can do something similar. Borrow a tunnel-boring machine... drill a long shallowly sloping tunnel into solid bedrock. Make a chamber at the far end, put your stuff there. Seal up your tunnel using the gravel from drilling the tunnel, with concrete mixed in to make it solid.

During the "dark ages", no-one will have the tech to break through that, or even find it.

When we are back to present day tech, some geologist will notice a very peculiar long, straight and uniform echo on their ground penetrating radar. It is really strange, because none of the archives about nuclear waste or chemical waste speak of anything that is meant to be there.

Once they drill their way into the chamber, they notice that there are glass jars standing on pillars everywhere... a few may already have fallen, spilling something. It is hard to say what it is really... and... oops!!! CRASH ...there goes another one. Hm... smells slightly... sweet?

A few days later they are dead... from mercury poisoning. Dimethyl mercury to be exact.

Simple... effective... doesn't use exotic tech... leans on technology that is about to be, or is already, employed for extremely long term storage.


Make the artifacts themselves lethal. Or the place its in.

You'd need to guesstimate the technology level of the future explorers but you'd want a series of environmental hazards. Rolling stones, punji pits and *arrow launchers"? Amateurs the lot of them

Seed the place with toxic spores. Long lived, lethal mold. Radioactive walls and architecture that shields it. Until you open the door.

For that matter, a highly radioactive artifact that's going to give you serious radiation poisoning? Indy would have been caughing blood, and dying before he got out.


How about hermetically sealing it and filling it with a poisonous gas. Preferably one that is colourless, odourless and not too rapid acting, so as to deter entry. If there is nothing that fits that bill then booby traps that release something faster acting like sarin or chlorine.

  • 1
    $\begingroup$ Most chemical compounds will not last 500 years. Although maybe setting the temple below terrain level and somehow channeling CO2/CO from volcanic activity would work. $\endgroup$
    – Mike L.
    Oct 29, 2015 at 14:59
  • $\begingroup$ Perhaps remove all the oxygen and replace it with nitrogen. IIRC, you wouldn't realise that you weren't breathing air, you'd just pass out and die. $\endgroup$ Oct 29, 2015 at 15:08
  • 1
    $\begingroup$ nitrogen would tend to mix with oxygen. CO and CO2 are both heavier than air and displace oxygen, and have the effect you describe, more or less. $\endgroup$
    – Mike L.
    Oct 29, 2015 at 15:21

Instead of having the temple gradually collapse into a fissure as in "Indiana Jones and the last crusade", just detonate a nuclear bomb. Make sure the bomb is engineered to last thousands of years with no maintenance. It needs to be built out of non-corrosive materials. And instead of having a conventional battery to power the trap, it needs to run on a very low power nuclear reactor fuelled by normal uranium with a half life of 4.5 billion years.

  • $\begingroup$ Just to point out that half-life have nothing to do with how long a uranium can last in a nuclear reactor. Also that makes for a very complex machine that you cannot keep running for 500 years. It would be much simpler and reliable to make some kind of chemical battery that can be stored. Or simply storing sodium above a big bath of water, releasing it with a simple mechanical device. Sodium into water = lots of hydrogen for a fuel cell. Also nuclear weapons require maintenance... the explosives needed to fuse the.... hold on a second... see next comment. $\endgroup$
    – MichaelK
    Jun 4, 2016 at 23:40
  • $\begingroup$ Come to think of it, you do not need a reactor or a bomb... you just need something that goes critical. Like the Demon Core. en.wikipedia.org/wiki/Demon_core The big problem is that in 2015, you'd be in trouble as soon as you try to amass Plutonium-239 as a private citizen, no matter how rich you are. $\endgroup$
    – MichaelK
    Jun 4, 2016 at 23:45

After reading TrEs-2b answer, I'm inspired by this alternative:

Given that the Oak Island phenomenon is a natural sinkhole that fills in with debris after each episode of subsistence (other examples can be found, intact, for comparison), yet has proved an expensive distraction, use natural phenomena to fake an elaborate hiding place.

With a small investment, a natural formation could be made to look like a highly elaborate preparation. Especially if the people after your treasure are not geologists trained in local features, and once they start into it the natural/modified distinction will be obsured by actual rework.

So, you lead the treasure hunters to an expensive money pit and they stop looking. The real treasure was hidden somewhere else.


The answer that will surely kill all the explorers is as simple as it is unethical:

Go to the swiss alps and have yourself a bunker mined into the granite, just one access shaft. After construction, all ventilation equipment is removed. Then the art is brought in using scuba gear. Now comes the trap part:

Put the art on pedestals that glow in the water. Not the phosphorescence type of glow but the luminiscense of the cherenkov effect: By placing the art on pedestals made from nuclear waste material to achieve this, you have a radiation trap for the next 25000 years or more. By using enough ammounts distributed with air gaps, it should create an area of more than lethal radiation. 30 Gray1 is is lethal within 2 days... but if we use the Fukushima slag as pedestals we could achieve up to 530 Sieverts1 of background radiation in our halls, than this is enough to deadly irradiate the explorers if they are still in the access shaft and disrupt camera drones to the point of failure. Plus, the glowing skeletons of the workers that brought in the slag will serve as a warning to the wannabe Indiana Jones.

1 - Gray is the physical dose of radiation in 1 J/kg, Sieverts is the equivalent dose in the same unit, weightened by a factor d - for whole body the conversion factor d from Gy to Sv is 1 though.

  • Encase your artifact in graphite, which has a very high melting point.

  • Go to Stromboli, one of the three active volcanoes in Italy and a volcanic island.

  • Drop your graphite box containing the artifact on the Sciara del fuoco ("Stream of fire"). This is where lava flows to the sea every hour or so. Let the box be covered with lava.

enter image description here

  • Good luck to all those archaeologists trying to recover an artifact covered with 500 years of lava on an active volcano.

Dig a ** VERY DEEP** hole.

Put goodies in hole.

Put magic porridge pot in hole.

Say "Cook little pot"

Walk away.

Cataclysm and protection and cost efficient all in one pot.

Actually I'm not sure about cost efficient. I don't know how much a magic porridge pot goes for on Ebay these days

  • 1
    $\begingroup$ Magic is contrary to the reality-check nature of the question. $\endgroup$
    – JDługosz
    Jun 4, 2016 at 5:35
  • $\begingroup$ Any upvotes for sheer flippancy >:-> $\endgroup$ Apr 29, 2018 at 22:46

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