The Katholikon was built in 1695 on the site of an older church which had either undergone irreparable damage or was no longer meeting the needs of the brotherhood. Over its main entrance a marble founder’s inscription in Byzantine writing reads:
The divine and most sacred church
Of the honorable Forerunner
By commission of the Rt Rev. Abbot Arsenios
Guide of this church
The marble founder’s inscription above the entrance of the Katholikon.
The Katholikon is arranged on a four-pillar domed cruciform plan. Its main characteristic is two arches to the North and South influenced by the Byzantine tradition and used as chorus in the manner of Athonite churches.
It is made of hewn stone carefully connected with mortar. Large tufa pieces of the 15th or 16th century are positioned mainly on the eastern side, probably belonging to the earlier church.
Marble capitals depict a spiral acanthus motif. The scuffed edges of the façade resemble an architectural peculiarity of Venetian buildings of the 16th century.
The church's simple but imposing architectural features harmoniously entwine Byzantine and Western influences. The façade is decorated with a novel tiled meander on its side.
Its left side exhibits Byzantine art of the 11th century, possibly the only surviving parapet from the temple of the original church now used as ornament and depicts an eagle grabbing a hare with its claws and beak.
Part of a Byzantine iconostasis closure panel (thorakio) of the 11th century. Built-in at the façade of the Katholikon, it depicts an eagle grabbing a hare.
On its right there is the coat of arms of a Venetian lord of the 15th century, nodding to a likely affinity of the Monastery with the Latin Archdiocese of Nafpaktos (Lepanto) established by Tarantino Fillipo (1307 - 1499) or its Venetian administration (1407 - 1499). Between the two reliefs is the founder’s inscription.