meteora
Meteora is the name of a set of monasteries built on top or into an area of unusually shaped and enormously huge columns of rock in Thessaly (a part of Northern Greece) with many natural caves. A Google Earth bird view shows the whole terrain including the village of Kalambaka.

Virtual aerial view ©Google Earth
Paleolithic people were using some of the natural caves in the area as a shelter from cold, heat and wild animals. According to radiocarbon analysis paleolithic the first traces of humans were found around 50.000 years ago.
There are no traces of human settlements during the classical Greek period.
Christian hermits have been living in caves around Meteora since 800 CE, their traces have been found by archeologists. Starting from around 1300 CE orthodox Greek monks built their housing on top of the rock formations, where they could live, work and pray in seclusion. The fortifications were necessary because of the frequent Ottoman invasions of Thessaly. Access to the monasteries was only possible via ropes or ladders, which could be pulled up in case of unwelcome visitors. In the subsequent centuries 24 separate monasteries were established, hundreds of monks lived there, and by and by impressive interior decorations were added (pics 12 – 16).
Nowadays only six places are still inhabited:
Varlaam (01)
Rousanou (02, 03)
Agios Stephanos (St Stephen, 04, 05 , 06)
The Monastery of the Holy Trinity (07)
Nicholas Anapausas (08)
The highest, oldest and largest monastery Great Meteoron (09, from left to right Nicholas Anapausas, Rousanou, Great Meteoron, Varlaam).
Originally there were only men in the monasteries. Two of them (Rousanou, St Stephen) have been taken over by nuns nowadays. Since 1988 the area is recognized as UNESCO world heritage, which of course meant that the monasteries had to open for the public. The visiting hours are limited for each place, but little is left of the original solitude for the monks and nuns. They are busy with organizing the steady flow of visitors and maintaining the buildings, museums and the interior decorations. St Stephen (pics 4,5 and 6) is only place with a large residential area where the nuns are still practicing hesychasm, the traditional way of Greek orthodox mysticism.