It is located under Cappadocia in Turkey Derinkuyu, an underground city that once housed 20.000 people. Its ancient name is Elengubu. It is located 85 meters below the Earth's surface and has as many as 18 levels of tunnels. This place was inhabited for thousands of years – Phrygians, Persians, Christians from the Byzantine era and many other peoples lived here. The Cappadocian Greeks left it in the 1920s, that is, when they were defeated by the Turks and fled en masse to Greece.BBC Travel".

Not only do the underground chambers stretch for hundreds of kilometers, but there are also more than 200 separate cities here, forming a vast "underground network". Derinkuyu was "rediscovered" by an unnamed local in 1963. Namely, his chickens kept running away and that's how they found this city.

The local then excavated the passage and was fascinated by what he found. Here, among other things, there were food warehouses, cattle stables, schools, wineries and even a chapel. Derinkuyu was included in the UNESCO World Heritage List in 1985.

Most of Derinkuyu is thought to have been built by the Phrygians

The exact date of construction is still unknown, and Derinkuyu is first mentioned in the work Anabasis, written by Xenophon in 370 BC. In that book he talks about people from Cappadocia who lived in underground houses. This phenomenon was unusual for him, considering that most of the inhabitants then lived in dwellings on the nearby rocks.

Most of Derinkuyu is thought to have been built by the Phrygians as they had the means to build complex underground structures and were one of the most prominent empires in Anatolia. This place was used to store goods, but it was built so that the inhabitants could hide from invaders. It is believed that during the Byzantine era, as many as 20 thousand people lived here.

Today, tourists pay around 60 lira to enter Derinkuyu. Of course, the tunnels are narrow and poorly lit, and it is remarkable that there is a ventilation system and a well dug at a depth of more than 55 meters.