The Monastery of Leimon is a men's convent, situated in the centre of Lesbos, at a 14 km distance from Kalloni, in a fertile basin. It was founded in Byzantine years and was inhabited until the occupation of the island by the Turks. The monastery was re-founded in 1526 by Saint Ignatios Agallianos, a significant personality who contributed in the rebirth of both education and the Church. At that time the well-known "Leimonias" school - which remained open until 1923- functioned within the monastery's enclosure.

The katholikon (main church) was built in 1526, at the time of the monastery's reformation and was repeatedly restored. It is a three-aisled basilica with the roof of the middle aisle higher than the other two and a double narthex. It is decorated with interesting wall paintings that date in the second half of the 16th and the first half of the 17th century. Worth mentioning is the wooden-carved gilded templon in the church's interior.

Today in the monastery there is an important library with manuscripts and a vestry.