This article discusses the discovery of ancient Egyptian temples in Sinai. When they say that archaeologists are digging up the remains of an ancient city, do they really mean that the basements, foundations, and lower areas of a settlement are being found, or do they mean the whole settlement intact? If they’re unearthing entire buildings, how do they end up buried in the first place?
The can be buried under sand in a sandstorm, under volcanic ash/mud/lava, and just with time. New soil is made over time, and eventually buries abandoned cities. I’m not explaining it very well.
In Egypt in particular, the sands move a lot. As I understand it, the Sphinx was once completely (or only mostly?) buried by sand until people dug it back out.
Elsewhere in the world, you can have other phenomena bury sites. Mesopotamian sites can be covered by many feet of mud after floods of the Tigris or Euphrates. In jungle areas, decomposing plant matter (leaves, etc.) can slowly bury sites, or at least fill up the interior spaces. We often don’t think of it, but cities also tend to bury the older versions of the city underneath. After a major disaster such as a fire or siege, the new city gets built right on top of the old one. (If you’re ever in Seattle, there’s a fascinating underground tour where you can see how rubble from earthquake damage was bulldozed flat and new buildings and streets put on top. Some buildings still have a functional “first” floor that is now underground).
In terms of digging up an ancient city, it’s usually not found in any kind of intact form. Often, what they’re finding are collapsed walls and foundations. They can recreate where buildings used to be, but aren’t necessarily finding much of the building itself. Often, stone blocks and other building components were scavenged to make new structures.
Cecil wrote a column on this subject.