The valley of Erdemli contains a Byzantine settlement from the 9th to 13th century. The main complex is the Saray Manastırı (palace monastery) with a decorated facade, a big cave church and several spaces on the bottom of the valley. The hillsides contain hundreds of caves with several cave churches and a cave mosque.
Cappadocia is a part of central Turkey. Eruptions of several volcanoes (e.g. Erciyes Dag, Hasan Dag) had covered the area with tuff. Erosion dug valleys and created an uncountable number of different shaped rocks. The tuff's ability to store water made the valleys much more fertile than the higher surroundings. After the arrival of the first people, they soon started to dig caves into the soft stone. By the time they developed the ability to dig cities into the underground with tunnels of several kilometers. A sophisticated pipe- and tunnel-system cared for fresh air and water, to enable the people to hide from enemies for a long time. In the 5th century hermits started to settle in the valleys and to paint their caves. In the next centuries more and more hermits and monks arrived and a rich cave-architecture with colourfull wallpaintings developed. The most famous are the churches of Goereme and the Peristrema Valley (=Ihlara Valley) between Ihlara and Selime. Today thousands of tourists from all over the world are visiting the area.