underground city

Vietnam's Cu Chi Tunnels make the list.

Beneath the historic foundations of the ancient Zerzevan castle in Diyarbakir province – southeastern Türkiye – scientists have discovered an incredible settlement.

In 1934, G. Warren Shufelt told the Los Angeles Times that he had discovered the remains of an ancient reptilian civilization beneath Los Angeles, USA.

Stories about people living in mines, caves or abandoned tunnels are not strange stories.

Unesco's Scientific, Educational and Cultural Organization has recognized Goreme National Park and Turkey's Cappadocia rocky area as a World Heritage Site in 1985.

A Turkish man while repairing the house accidentally discovered the tunnel leading into the ancient underground city thousands of years ago.

Archaeologists have discovered a network of tunnels, forming an underground city, buried deep beneath the mansion of Roman emperor Hadrian near Rome.

The image of the Noctis Labyrinthyus crater, announced by NASA, is believed by many to be the ventilation roof of an underground city on Mars.

According to Dailymail, after discovering a strange ant nest, scientists had to dump 10 tons of concrete and excavate to see the size of the ant nest.