A Man Knocked Down His Basement Wall, Discovering Ancient Underground City That Housed 20,000 People (Video & Pictures)

Inside the subterranean city — whose entrances connect to more than 600 private homes in the modern, surface-level region of Cappadocia — researchers found 18 levels of tunnels containing dwellings, dry food storage, cattle stables, schools, wineries, and even a chapel. The city was also equipped with a ventilation system that supplied its residents with fresh air and water.