Monastic mountains and deserts was the topic of a panel at the 21st International Congress of Byzantine Studies held in London in August 2006. Holy mountains and deserts are exceptional places, secluded from the world, places where communication with the divine is more intensive than elsewhere. Byzantine monasticism was characterized by the coenobite, lavriote and solitary ways of life. An important factor was the distinctive morphology of such locations, whose dramatic beauty and natural landscape features-precipices and caves-inspired contemplation and ascetic endeavours. In the seven contributions presented here, this phenomenon is illustrated by examples from different regions, either in the Byzantine Empire itself or in areas under Byzantine cultural influence. Panegyrics on the 6th century Pachomian archimandrite Abraham of Farshut supply information about the impact of the Council of Chalcedon on the coenobitic communities of Upper Egypt. Flourishing at times during the middle Byzantine period were the monastic mountains of Auxentios, Bithynian Olympia and Kyminas (to the east and, respectively, to the south of Constantinople). Lazaros, the founder and abbot of the monastic community on Mount Galesion had difficulties with ecclesiastical authorities as well as with his own monks. Already in antiquity, Ganos was well known as a holy mountain; the Turkish conquest of this region on the coast of the Sea of Marmara did not quench the Byzantine monasticism. In medieval Serbia, a powerful influence on the organization and nature of monasticism came from the holy mountain of Athos. Gregorios Sinaites, a prominent representative of Hesychasm in the 14th century, founded a monastery in the border area between Byzantium and Bulgaria; it existed for only a short time and its location is still disputed. The final contribution presents the 9th and 10th century churches and monasteries of the Georgian Sinai, present-day Artvin Ili in Turkey.