Patmos is a small Greek island in the Aegean Sea, one of the northernmost islands of the Dodecanese complex.
Patmos is one of the most religious Greek Islands because it is where Saint John the Divine had its revelation and wrote the Apocalypse. Many orthodox people still come to the island on pilgrimage - hence the coachloads of people heading up to the cave where St. John wrote.
The churches and communities on Patmos are of the Eastern Orthodox tradition. In 1999, the island's historic center Chora, along with the Monastery of Saint John the Theologian and the Cave of the Apocalypse, were declared World Heritage Sites by UNESCO.