Nevsehir, Turkey

A little girl is running down the hall of an underground city in Cappadocia. This historical region dates back to 3,000 B.C and has numerous underground dwellings, chimneys and volcanic landscapes.

Photo: Chris McGrath/Getty

Nevsehir, Turkey

The sun sets over a cave hotel during spring. The region of Cappadocia has major success when it comes to the Asian tourist market.

Photo: Chris McGrath/Getty

Luray, Virginia, US

A group of tourists admire the natural architecture of the Luray Caverns.

Photo: Karen Bleier/AFP/Getty

Badana

A military fighter explores the kitchen of an underground tunnel created by ISIS last month. Apparently, the ISIS fighters had built many tunnels so they could go from one place to the other secretly.

Photo: Bram Janssen/AP

Judean Desert, Israel

Two volunteers of the Israeli Antique Authority at an excavation site known as the Cave of the Skulls.

Photo: Ronen Zvulun/Reuters

Hunan province, China

Workers look at the tunnel of a future subway in Changsha.

Photo: Reuters

Saint-Engrace, France

A man walks on a slackline in a cavern of La Verna, one of the largest underground places in the world, at the Gouffre de la Pierre-Saint-Martin.

Photo: Iroz Gaizka/AFP/Getty

Alps Mountains

The turbine of the ‘Romanche Gavet’ hydroelectric plant located inside the French Alps.

Photo: Jean-Pierre Clatot/AFP/Getty

Idlib, Syria

Children at an improvised classroom inside the cave of the Tramla village. The region is controlled by Syrian rebels, so people have set up a school underground for 120 children.

Photo: Khalil Ashawi/Reuters

Erstfeld, Switzerland

A group of artists perform at the opening party of the longest railway tunnel in the world at Gotthard, which runs under the Alps.

Photo: Fabrice Coffrini/AFP/Getty