The Holy Monastery of Dionysiou was built in 1366 by Saint Dionysios upon an enormous rock on the southwestern side of the Athonite peninsula, close to the coast, and is dedicated to Saint John the Baptist.
The emperor of Trebizond, Alexios Komninos III, economically assisted the reconstruction of the monastery, thus explaining why the monastery was also called «Monastery of the Great Komninos.»
Exquisite frescos adorn the Katholikon and the Refectory of the monastery. The frescos in the temple were painted by Tzortzis between 1546 and 1547, while the monks Daniel and Merkourios painted the Refectory.
The frescos which are found just outside of the Refectory contain depictions which interpret the book of Revelation. The explosion of an atomic bomb, firing of missiles, attack of warplanes and tank warfare were painted almost five centuries ago prophetically.
The right hand of Saint John the Baptist is treasured within the monastery, together with the icon of the Holy Virgin «of the Akathist.» It was with this icon in his hands that the Patriarch Sergios supported the struggling soldiers during the siege of Constantinople by the Avares in 624.
The library of the monastery is quite extensive, containing more than 1,100 manuscripts, many of which are adorned with miniatures.