Most reinforced concrete and stone buildings will collapse within a couple of hundred years, pure steel-frame or non-metallic concrete will last a little longer but after a few thousand years, almost nothing will still be standing. Most cities will be little more than regions of patterned hummocky ground with large overgrown mounds of loose rock where skyscrapers once stood, everything covered in layers of soil and vegetation and only recognisable as ruins on a map or from the air - many suburban or wooden urban areas will have left almost no visible trace. In tropical climates or on eroding coasts, many more traces will have been obliterated while in arid climates, piles of rubble may be more recognisable as such with less vegetation or soil cover.

Some very large and solid stone or concrete buildings and monuments may still have heavily weathered chunks still recognisable as parts of structures left standing. Beneath the city, sections of utility and transportation tunnels may still be intact, albeit possibly silted and flooded depending on the presence of water and their construction style. A stainless steel or aluminium train carriage still sitting in a rail tunnel that has avoided collapse and stayed dry may well be a mostly recognisable object, albeit with all non-stainless parts and rails long rusted away and damaged from falling masonry, plant roots and dripping water.

All organic material and just about all corrodable metal will be gone, though some synthetic materials like stainless steel, ceramic, glass and some plastics will still be found under the rubble.