The Holy Monastery of Philotheou stands among chestnut trees on a plateau on the north-eastern side of the peninsula, near the ancient Temple of Asclepius. It was founded by the Blessed Philotheus, a contemporary of St Athanasius the Athonite, around the end of the 10th century.
Among the Byzantine Emperors who made donations to the Monastery, the names of Nicephorus Botaneates in the 11th century, Andronicus II and Andronicus III and John V in the late 13th and in the 14th century stand out. Among Serbian princes, Stefan Dushan (1346) helped to provide the manpower for the Monastery. In the 14th century, St Theodosius, subsequently Metropolitan of Trebizond, and brother of St Dionysius, founder of the monastery of that name, was a monk in the Monastery. During the early years of Turkish rule, in the early 16th century, the Abbot Dionysios, known as the Blessed Dionysios of Olympus, succeeded in turning it from an idiorrhythmic into a coenobitic monastery. However, the reaction of Bulgarian-speaking monks was such that he was forced to leave the Monastery. In about the mid 17th century, the Tsars of Russia gave permission to the monks to go there every seven years on alms missions. The policy of support for the monasteries was also followed by the Greek princes of the Danubian provinces. Grigorios Ghikas was one of the Monastery's best known benefactors.
In the 18th century the missionary of modern Greece St Cosmas the Aetolian was a monk at Philotheou. A fire which broke out in 1871 left unscathed the new katholikon, which had been built in 1746 on the foundations of an older church, but caused the Monastery economic problems, so that in 1900 the Holy Community took it under its guardianship. Of the other buildings of the Monastery, the holy water phiale is of fine white marble, and the refectory was extended in the 16th century. Philotheou has six chapels and three outlying chapels. Of its 12 kellia, half are now uninhabited. Philotheou prides itself on the possession of the miracle-working icon of Our Lady Glykophilousa, and of our Lady Gerontissa.
Among the objects kept in the sacristy, pride of place goes to the right hand of St John Chrysostom, a piece of the True Cross, other relics of saints, vestments, and sacred vessels. The library contains 250 manuscripts, two liturgical scrolls, and about 2,500 printed books (of which some 500 are in Russian and Romanian). The Monastery is dedicated to the Annunciation of the Blessed Virgin, and since 1574 it has occupied twelfth place among the Athonite monastic foundations. Since 1973 its has followed the coenobitic system. At present it has about 60 monks.