Zygos Monastery is an old Mount Athos monastery, which was built in the middle of the 10th century and was destroyed shortly before 1198. It is located about 2 km east of Ouranoupolis, just outside Mount Athos, in a place also known as "Frangokastro »(Just 40 meters outside the current boundary of Mount Athos). It is one of the oldest monastic institutions in the Athonite peninsula. It came to light from archaeologists in 1984.

In the excavation of the former Mount Athos Monastery of Zygos, known to all as the only Mount Athos monastery that women can now visit, the visitor will see the castle, the towers, and especially the katholikon of the monastery of Zygos, which archaeologists bring to light. The castle consists of five construction phases, all older than 1211. The area inside the walls reaches 5.5 acres and the walls had 11 towers.