The most important aspect of real estate is location, location, location. Places that people are living are places that other people would want to live. That’s why cities are in the same place for hundreds to thousands of years even if they get destroyed from natural or human means.
Another factor is that people only recently had access to trucks and other heavy equipment to dig out and move debris and dirt. In the past, if you wanted to build new things on a property, you just demolished what was on it, filled the holes with dirt that people didn’t want, and built on top of that. This buries the old structures under the new ones.
Cities also import more material than they export. Building materials are not harvested inside the city so they need to come in from somewhere. Crafters take in more volume of raw material than they generate in product after carving it down. And in general, trash and waste builds up in a city. This helps provide some of the “material” to cover up the old structures and grow a city on top of an older version of itself.
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