Monastery of Saint John the Theologian, Byzantine monastery on Patmos island, Greece

The Monastery of Saint John the Theologian is a fortified complex on the highest elevation of Patmos island, featuring massive walls, defensive towers and several church buildings. Within the outer walls lie courtyards, cells and a main church connected by narrow passages and stairs.

Christodoulos began construction in the late eleventh century after receiving the island from the Byzantine ruler. Over the following centuries, additional fortifications were added to guard against raids by pirates and foreign fleets.

The monastery is named after St John of Patmos, whose visions of the apocalypse, according to the text, came to him on the island; the Cave of the Apocalypse nearby is where tradition places their writing. Ceremonies dating to the early Christian period are still practised inside the walls, and the monastery has remained a pilgrimage site and centre of Greek Orthodox learning since 1088.

Visitors should wear long trousers or skirts and cover their shoulders when entering the grounds. The climb to the summit follows steep paths, so sturdy footwear is recommended, especially in warm weather.

The library holds at least 330 manuscripts, 267 of them on parchment, among them 82 New Testament manuscripts. The monastery also keeps the skull of Saint Thomas the Apostle as a relic. The imperial chrysobull of Alexios I Komnenos, granting Patmos to Christodoulos, is preserved here.