The monastery of the Archangel Michael Roukouniotis was built by the Knights of Saint John in the 15th century. The monastery was built on the ruins of an ancient temple. It is situated on the western side of the island, about 5 km from Simi Town.

Roukouniotis Monastery is built like a fortress and the monastery has two temples, the lower temple containing some significant murals from the 15th century. Every year, on the 8th of November, the monastery celebrates its patron saint with a Holy Mass and a big feast. Outside the monastery walls, there is a 100-year-old cypress tree.