The Monastery of Agios Ioannis Theologos on Patmos is a unique example of medieval monastic architecture and a place of considerable religious interest, being one of the largest monasteries in the Aegean. Tradition has it that John, the beloved disciple of Jesus, was exiled to barren Patmos in around 95 AD, during the persecutions of Emperor Domitian; it was during his stay on the island that John wrote two of the religious texts central to Christian faith, the Gospel According to John and the Apocalypse. Inextricably linked to this tradition is the founding of the monastery by Blessed Christodoulos Latrinus in 1088.

Having petitioned Emperor Alexius I Comnenus , he managed to secure a chrysobull granting him the island and other privileges so as to found a monastery dedicated to the Evangelist.

The monastery was erected on the summit of the hill, over the remains of an ancient temple and an early Christian basilica . Over time the settlement known as Chora (the island capital) grew up around it, merging to form a densely built and labyrinthine architectural ensemble.

The monastery complex is surrounded by an irregularly shaped, many sided medieval wall 15 m in height. The interior is on several levels, including cell wings, auxiliary buildings, galleries and chapels dating to the 16th and 17th century, built around the catholicon as their focal point. The latter is a late 11^th century composite four-column cross-in-square church , with attached chapels dedicated to the Virgin Mary and Christodoulos. The surviving wall paintings are fine, rarely encountered depictions of evangelical scenes probably painted by a Cretan School artist, dating from the second decoration phase in the early 17th century. The chapel of the Virgin Mary has an important fresco ensemble displaying the monumental tendency of the late 12^th century. The famed monastery library and sacristy house treasures and heirlooms of inestimable historical and artistic value, such as rare collections of Byzantine and post-Byzantine manuscripts, imperial documents, books, icons and miniature works. The Monastery of Agios Ioannis Theologos on Patmos (an impressive architectural monument and repository of Byzantine culture), the Cave of the Apocalypse and Chora (Patmos town) were placed on the UNESCO World Heritage List in 1999, as a prominent Greek Orthodox pilgrimage centre of outstanding architectural interest.