In Preventing a word from being spoken, I asked about how to prevent a word from being spoken, and the means I chose was to change humanity so that humans can no longer say the Word.

To that end, I am proposing a great magical ritual, the building of the Tower of Babel. The nature of the ritual is that the tower is built, and when it is complete, it is deliberately collapsed, and in its breaking, breaks the people apart, making them unable to understand each other, and also unable to say the forbidden Word.

My question is a problem of engineering. I want the people in my story to build as high a tower as possible, using materials that were available circa 3000 BC, or could be made during that period by people of the day using modern circa 2000AD knowledge, though without significant modern infrastructure. The tower must be stable, able to remain standing during and after construction given the weather and geological conditions in an area like Mesopotamia.

However, the tower must also be constructed so that it can be collapsed on demand, with a minimum of effort, and preferably without explosives. A method that would allow a single person triggering the collapse to be able to retreat to a safe distance before the structure collapses would be preferable. It would also be preferable if the mechanism by which the tower could be collapsed was not immediately obvious to those constructing the tower.

While descriptions of the biblical tower of Babel exist, they need not be considered to represent constraints on the design of the tower in this question.

Given these constraints, how high a tower might be constructed, from what might it be constructed, and how could it be collapsed on demand?

  • 1
    $\begingroup$ Obviously it's your story, your rules, but I'm a little confused why you're apparently going to have a magical ritual change the language of everyone on the planet instantly but you need it to involve a completely mundane tower without so much as a pile of gunpowder. $\endgroup$
    – Cadence
    Commented Apr 23, 2022 at 7:13
  • $\begingroup$ @Cadence Time travel is involved, and the time traveller doesn't want to introduce gunpowder thousands of years before it was invented. The tower won't be mundane, since each piece will be enchanted, but it must be constructed and demolished in a mundane manner. The tower must collapse, not explode. $\endgroup$
    – Monty Wild
    Commented Apr 23, 2022 at 7:51
  • $\begingroup$ It sounds like a tumbling tower design might work. Get the game and experiment. $\endgroup$
    – David R
    Commented Apr 23, 2022 at 14:24
  • $\begingroup$ Can your time traveller look up reliable geological/historical records? Because, say it's Earth, you just need to build it in Sparta in 464 BC, or Ephesus in 17 AD, or even Pompeii in 79 AD... $\endgroup$
    – Ottie
    Commented Apr 23, 2022 at 16:59
  • $\begingroup$ @Ottie, technically, it has to be built in Babylon. $\endgroup$
    – Monty Wild
    Commented Apr 23, 2022 at 17:29

3 Answers 3


Large Tree

enter image description here

The tower is supported on one corner by a pine tree. The trunk is exposed. When it is time to collapse the tower, use an axe to chop a wedge out of the trunk. The tree cannot support the weight of the stone above. It breaks in half and takes the rest of the tower down with it.

  • $\begingroup$ Very nice solution. There's also the pyromaniac's alternative twist.. say no more. $\endgroup$ Commented Apr 23, 2022 at 16:13
  • $\begingroup$ @EveninginGethsemane That was another thought. But it will take a while to burn to the middle of the tree. So it's not exactly "on demand". There are also design considerations to allow enough air in. $\endgroup$
    – Daron
    Commented Apr 23, 2022 at 16:32
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    $\begingroup$ Downvote because there are no pine trees in that area. $\endgroup$
    – Willk
    Commented Apr 23, 2022 at 17:14

I would say a dome structure, something like the Pantheon in Rome with its 43 m, can suit your scope:

  • it was built with Roman technology. Nothing fancy as the modern one, but still relying on materials available at short hand
  • it is still today the largest unreinforced concrete dome
  • being a dome, its stability is ensured by the keystone, in this case replaced by a ring

The keystone/ring is also the key for its demolition: ensure that it is held in place by lead bars, and when you want to demolish it, have some mercury seeping on the lead.

Lead will dissolve in mercury while the perpetrator goes away, and once the bars are gone the dome will collapse.

  • $\begingroup$ That's not exactly a tower, now is it? $\endgroup$
    – Monty Wild
    Commented Apr 23, 2022 at 9:51
  • $\begingroup$ @MontyWild, yourself have stated "descriptions of the biblical tower of Babel exist, they need not be considered to represent constraints on the design of the tower in this question." $\endgroup$
    – L.Dutch
    Commented Apr 23, 2022 at 10:16
  • $\begingroup$ Question states "the mechanism by which the tower could be collapsed was not immediately obvious to those constructing the tower.". How is that met here ? You need a lead ring. You'd need a wide ring around the keystone. The required diameter of this "collapse ring" depends on the weight (thickness) of the dome construct. Also, the mercury should be administered evenly, on a safe distance using a nifty mechanism. And the makers of the dome were not aware of it ? $\endgroup$
    – Goodies
    Commented Apr 23, 2022 at 14:52
  • $\begingroup$ I meant that the tower need not necessarily be built from fired clay bricks and pitch as per the descriptions I've seen. It would still need to be a 'tower' not a 'dome'. $\endgroup$
    – Monty Wild
    Commented Apr 23, 2022 at 15:36

Stack of rocks.

Quartzite has a compressive strength of 39870 psi aka pounds per square inch. That is the pressure it can withstand before structural failure. Quartzite mass is 165 pounds per cubic foot. I am just going to go full on imperial here it looks like.

So your builders, or stackers, have elegant quartzite blocks each measuring 1 cubic foot. Each has a face of 144 square inches to absorb 39870 pounds per square inch so a cubic foot block would need 39870 * 144 square inches or 5741280 pounds to crush it. Strong stuff! 5741280 / 165 lbs per block = 34795 blocks, each measuring a foot. We are only going to use 34794 of them for obvious reasons but I think that stack should serve your purposes well and also be eminently and easily topplable.

Did you know that Sioux Quartzite is a natty shade of pink, and sparkly? Take a gander!

sioux quartzite

I think that will help too.

One might ask how the upper reaches of this stack might be stacked. I think it will need to be done using hot air balloons, hoisting the blocks up and then so gently placing them.

I forsee protests! "Nay!" they go. "Nay - the compressive strength of the soil outside the bar where we are putting this up cannot withstand such force! Long before it reaches maximium height, the stack will drive itself into the yielding earth!"

That may be a good thing and allow your stackers to forgo the balloons, which were to be the subject of other protests. Yes, the stack does descend into the earth. That limits how high it can get but not the total extent. Stackers can effectively stack down. Then when the requisite number of 34794 blocks is stacked, the earth surrounding the buried extent of the stack is excavated away to reveal the stack in all its pink magnificence!


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