In my setting, humanity has largely—if not entirely—gone extinct on Earth. I was curious about what would remain of modern human architecture after around 3 millennia of no upkeep. Primarily urban buildings, larger cities, etc. I understand that wood-based structures would deteriorate without maintenance pretty fast. But what about metal, concrete, and other more hardy structures? Also, geography/terrain change is something I'm curious about. Would much of anything be left on the surface, or like much of Rome would whatever remains be buried?

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    $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Commented May 24 at 1:45
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    $\begingroup$ It's nothing against you or your question, but some form of this question has been asked over and over and over on this Stack. The only difference has been the length of time - otherwise they're all duplicates of each other. Given that the pyramids and other ruins have exceeded 3,000 years, this really boils down to location, which you haven't specified (and it needs to be exact, longitude/latitude exact). Generally, dry locations preserve things. Wet locations destroy things. Wood rots faster than steel rusts. At the top of the list is stone. Plants speed up destruction. Where's your city? $\endgroup$
    – JBH
    Commented May 24 at 3:50
  • $\begingroup$ Could you edit to focus on one topic. E.g., geography / terrain change? We do like focused questions at Stack Exchange! This will help you get a more focused answer. $\endgroup$
    – elemtilas
    Commented May 25 at 0:50

2 Answers 2


The Pyramids lasted 5000. The Parthanon 2,500 Contemporary structures, 100 years average. The dead sea scrolls lasted because they were stored in a dry salt cave.

Stone, lime mortar, clay fired bricks are the most longest lasting materials. real question is What climate would they be in. Dry/warm climate they'd last essentially forever in some recognizeable form. In humid climates they'd fester growth and vegetation like the pyramids of maya/aztec society.

enter image description here

Go down the list of building materials used by society today/past. Be it old, pre 20th century and newer materials today used last 150 years. Of the old, we have: Limestone, Marble, Lime concrete, Clay fired bricks, ceramic tile (terracota), Sandstone, Granite, Roman style concrete (volcanic ash), and Wood timber (aged centuries old growth often treated in pitch/salts/metallic salts)

Modern building materials include Portland cement and it's concrete, Steel Reinforced concrete, Sandlime bricks, Carbon steels, Aluminum, Laminated plastics, new growth timber (often less 40 years old) or reconstituted wood (plywood/particle board)

All of the modern building materials are popular in modern construction because..

  1. cheaper
  2. easy to mass produce Though they are "Cheaper" in the short term; because many of these materials share a common short life expectancy. Where as the vast majority of "old School" materials their virtue is their long, Near infinite shelf life. Hope Benegal, a British researcher (1888-1979); albeit mainly service acoustics and architectural history; studied building designs especially Post-war buildings in England. Reminded best building materials have long/infinite shelf life; essentially inert and last long periods of time even in presence of various weather/geochemical forces. The weakness of modern materials, especially metals and metal laced concretes is their "Coefficient of expansion" which makes them crack/fall apart if allowed to grow and shrink in changing weather patterns.

Another book "World Without Us" chronicles thought experiment of human development and buildings if society were gone and incapable of repairing them. In short reinforced concrete/glass buildings would inevitably break, fall apart after about 50 years and their steel frame bodies after 100-300 years.

Massive concrete structures like Hoover dam would last millennia but would inevitably fail as unchecked leaks and pipes would cause internal flood. Wooden houses would slowly rot without maintenance of their timber succumb fungus, termites and thermal shock.

Structures built in/near wild areas especially tropics would invearibly fail. Dams, canals, pools and lochs would fill with sediment and vegetation. enter image description here

the longest lasting effects human structures are durable plastics, special alloys (Bronze, titanium, aluminum) and certain stainless steels. Any buildings with lime/concrete based foundations, brick buildings and MASSIVE concrete structures.


It depends. In naturally dry areas, your structures might survive for millenia. If you have a area, that is naturally poor regarding moisture and rain, you can keep mumies and structures for long time. https://en.wikipedia.org/wiki/Chinchorro_mummies

People actually mummify just dying under these conditions. https://i.redd.it/2mvr0mkhli071.jpg

Then there is chaco canyon, again dry and thus naturally preserved. https://en.wikipedia.org/wiki/Chaco_Culture_National_Historical_Park

Water, Plants and thus nature are the natural enemies of preservation.

Thus i conclude, that in a dry location, with a "eternal" material like porcelain, that and poisonous material as defensive (lead, arsenic) artifacts could actually survive for quiet some time (10.000 of years). That is unless there is heat stress or other ablative weather phenomena like sandstorms.


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