A 6-story underground city in Turkey with a population of 20,000

The Turkish province of Nowshera is famous for its archeology, but its Derenkyu district is unique in that it has the remains of a vast underground city that is about two and a half thousand years old. The city is a six-story building that extends 200 feet below the ground and once housed 20,000 people.

The city is known as the "Derenkyov Underground City", located about 750 kilometers southeast of the Turkish capital, Istanbul.

The city's streets, shops and houses are all underground. Interestingly, the underground city also had separate areas for livestock and other pets, as well as fresh air.

There is a network of stairs and terraces that go down from floor to floor. In addition, there are small and large corridors that connect different parts of the city.

The city flourished during the Byzantine period and was used by the Byzantines to ward off attacks by Arab Muslims from the eighth to the twelfth centuries AD, while at the same time it was connected to other nearby underground cities by tunnels.

Later, local Christians took refuge in the city to escape Mongol invasions and other wars.

However, after the First World War, the Christians were expelled and the city became uninhabited. Later, in 1963, the site was taken over by the Turkish Archaeological Department, and tunnels and underground structures were discovered.

Fifty years ago today, the city was opened to tourists and today it is one of the most important historical monuments in Turkey.