The Monastery of Zygou is an exceptional edifice, structurally belongs to the Athonite architecture. It is located almost 2km east of the city of Ouranoupolis and 40m just outside of Mount Athos "borders". The exact locale is also known as “Fragokastro”, name which derives from a Frank lord who have settled in the Monastery in the early 13th c. It was established in the early 10th c and it seems to be one of the oldest monastic institutions on the Athonite peninsula. It was discovered by the archaeologist Joachim Papaggelos and his team, on 1984.
The name “Zygou” was first referred on a document of 942, in which it is not specified if this name refers to a location, a monastery or a settlement. Later on, the year 992, a second source confirmed the existence of the Monastery, when it was already an important monastic center with a significant part in the operation of the Athonite state. In the early 11th c., the initial building structure included castle and towers, expanded and the new Catholicon, main church building, was built. The monastery was abandoned in the late 12th century for unknown reasons and it was granted to the reestablished Holy Monastery of Chilandari.