Andromonastiro (Ανδρομονάστηρο) is a Byzantine monastery fortress founded at the end of the 12th century. Since it was built like a fortress, it contributed significantly to the Greek War of Independence of 1821, where it suffered a lot of damage from Ottoman troops. In 1785, and in order to halt the decline of the monastery, it was dedicated, as metochi (= embassy church), to the famous monastery of Agia Aikaterini on Mount Sinai. They sold the complex in 1929 and in 1862 it was granted to the Voulcanou Monastery.

Andromonastiro stands out for its remarkable fortress-like architecture, with buildings from different periods and various uses. Thecomplex consists of a three-storey building with the dining room, a two-storey wing with the monks' cells, storerooms, stables and the wine press and another two-storey building with the main entrance to the monastery.

The katholikon (main church) of the monastery was built at the end of the 12th century on a holy place, a spring with drinking water, which still gushes today in an underground vaulted space. A second construction phase took place in the 17th century; in the middle of the 17th century, the northern chapel of Saint Catherine was added to the church. The oldest frescoes date back to the middle of the 13th century. The newest frescoes belong to the 17th-18th century and are located in the lower perimeter zone of the church.

The monastery, which was in ruins for many years, has been completely restored since 2011. Nowadays it is considered being the most impressive monastic complex in the Messenian countryside and one of the most beautiful in the Peloponnese.