Located in Cappadocia, Derinkuyu is an ancient underground city that served as a hiding place for thousands of people during times of conflict.
This massive underground city in Beijing was built during the Cold War as a shelter in case of a nuclear attack.
Montreal Underground City is a vast network of interconnected tunnels and shopping malls.
Krakow features a stunning underground complex that includes chapels, sculptures, and even an underground lake.
Cu Chi Tunnels are an intricate network of underground passages that were used for hiding, transportation, and communication.
Setenil de las Bodegas is a unique town in Spain where many of the houses are built directly into the rock, creating an underground-like atmosphere.
Matmata is a village where people have been living underground for centuries, using natural caves for shelter.
Cavusin features a complex network of tunnels and chambers that were once inhabited by early Christians.
Coober Pedy is a town where many of the residents live in underground homes to escape the extreme desert heat.
Shinjuku Gyoen National Garden is used for government facilities and emergency evacuation.