Photo shows the Meteora monasteries, about 350 kilometers northwest from Athens, capital of Greece. Meteora means "Suspended in the air" in Greek. In a region of almost inaccessible sandstone peaks, monks settle on these "columns of sky" from the 11th century onwards. Twenty-four of these monasteries were built, despite incredible difficulties, at the time of the great revival of the eremitic ideal in the 15th century. Their 16th century frescoes mark a key stage in the development of post-Byzantine painting. Now there're six monasteries open to public, including two nunneries. The Meteora monasteries were inscribed onto UNESCO's World Heritage List in 1988.