The most iconic example of ancient underground engineering is in Turkey’s Cappadocia region . This was no mere cave; it was an 18-level deep metropolis that could house up to 20,000 people.
Today, underground cities are more about escaping the weather than escaping an invading army. Modern subterranean networks are booming in extreme climates. Underground Cities
In Saudi Arabia, the "Vault" project aims to create a vertical underground community carved into the mountains, flipping traditional urban sprawl on its head to preserve the desert surface. The most iconic example of ancient underground engineering
3. The Future: Ecological Preservation and "Inverted" Skyscrapers 000 people. Today