Sit at the edge of a rock, let your mind travel million years ago and imagine that you wet your feet in the water of a big lake. A lake covering the whole Thessalian valley. Look at the horizon and imagine the lake drying gradually and recovering all this natural beauty in front of you. This is the most possible option of how all these were created. You are in front of a geological phenomenon universally unique, where words like admire, unexplainable, impressing which we usually find in many writtings can describe it's size only to one point.
The Byzantine monasteries on Meteora grew out of the need to avoid Turkish persecution in the 14th c. The inaccessible peaks provided safety for Greek Orthodox monks. Until recently, access to the monasteries was by rope ladders and baskets. Today the monasteries are all connected by a series of paths and roads. Artistic and religious culture of the Greeks during foreign occupation was kept alive here, and that is why there is so much of interest for the decorations and frescoes, being a fundamental stage in the development of post-Byzantine painting. Further more the Orthodox spiritual life and exercise have provoked the admiration and interest of people all over the world. Today these monuments are, deservedly, a World Heritage Site.
Concerning the visit to the monasteries, do not hurry. Spend as much time as you can and walk around the area. 6 monasteries are open to the visitors, one better than the other with a lot of religious treasures. Notice how they are built and how you can reach them by bridges or stairs in the rocks. Look at them from below. Look at the details on the sandstone rocks, climb them and enjoy the view.