The monastery was named after a mid-14^th century monk named Barlaam, who was the first to climb the rock; he then proceeded to build a chapel dedicated to the Three Hierarchs. Foundation of the monastery is nevertheless attributed to two brothers, Theophanis and Nectarius Apsaras, who settled on the rock in around 1517. With the help of two other monks they set to repairing the buildings erected by Barlaam, and in 1541 added the catholicon dedicated to All Saints. It was in this period that the monastery acquired significant estates, flourishing until after the death of Theophanis (1544) and Nectarius (1550).

Another person of significance for the monastery was an 18^th century monk named Brother Christopher, who catalogued the archives and copied a number of historical texts, some of which are now exhibited in the monastery museum.

Access to the Monastery is gained via a flight of 107 steps, leading visitors to the top of Barlaam’s rock. To the right lie the hospital, the chapel of St Anargyroi, the catholicon and the tower, while the refectory, the small Church of the Three Hierarchs, the cells and the hostel are on the left.

The monastery catholicon is a cross-in-square— tetrastyle triconch church, rapidly built of rubble masonry. The interior is decorated with wall paintings of high artistic merit dating to two distinct phases. The bema and nave were adorned in the first of these, in around 1548, and are attributed to the Theban artist Frangos Katelanos, while the lite was painted in the second phase in 1566. The church was partially redecorated in 1780 and 1782 with funding from Bishop Parthenios of Stagi. The particularly rich iconographic program follows the Mount Athos tradition, and has likewise been attributed to Katelanos, founder of the Northwestern Greek School of painting.