The Dionysiou Monastery is located on a rock 80 m above the southwest coast of the peninsula of Mount Athos. Dedicated to St. John the Baptist, Dionysiou is sometimes called Nea Petra because of its setting. It was founded between 1356 and 1366 by the monk Dionysios (born 1316), a native of Koresos in Macedonia and former monk at Philotheou. As a result of the mediation of his brother Theodosios, who became metropolitan of Trebizond in 1368/9, Dionysios was able to secure the patronage of the Trapezuntine emperor Alexios III Komnenos. The latter became the ktetor of Dionysiou, financing the construction of its principal buildings. In 1374 the emperor issued a confirmatory chrysobull; at its head are depicted Alexios and his wife Theodora. The monastery also received property and fiscal exemptions from the emperors in Constantinople. Dionysiou was declared a patriarchal monastery in 1389. The archives contain 28 Byzantine documents dating between 1056 and 1464. In the library are approximately 237 Greek manuscripts of the 15th century or earlier. Its most precious possessions are a richly illustrated lectionary and an 11th-12th-century copy of the homilies of Gregory of Nazianzus. An ivory plaque depicting the Crucifixion above a scene of the soldiers casting lots may be of doubtful authenticity.
Oxford Dictionary of Byzantium