The first in hierarchy and size is the monastery of Agia Layra. The construction of the building began in 963 by Saint Athanasius the Athonite. . It is one of the richest monasteries of the mount because it possesses important religious relics and manuscripts. It is celebrated on 5 july in the memory of Saint Athanasios.
The monastery has two chapels, Agioi Saranta and Agios Nikolaos. Also relics, the stick of Agios Athanasios, the crown and other objects of emperor Nikiforos Fwkas are kept there. Nikiforos Fokas and Ioannis Tsimiskis were the two major donors for the construction of Agia Layra.