In 1004 the Tuscolo hills welcomed a group of monks. An old holy man arriving, anxious to find a place to build a monastery to gather all his brothers. It was St. Nilus, born in Rossano, in Calabria, from a Greek family. At that time Calabria was under the Byzantine rule and was Greek in language, culture,and spiritual and liturgical tradition. Nilus had founded several monasteries in Calabria and in Campania. Though a humble saint, he was held in high esteem by Princes, Emperors and Popes. Having flown from place to place to avoid all honours, he finally wanted to reach Rome to end his days in peace.
St. Nilus
The center of the life of the Monks of Grottaferrata is the Divine Liturgy (Holy Mass) and the Liturgy of the Hours (Divine Office).
The Byzantine liturgical rite properly belongs to the Church of Constantinople, the ancient Byzantium, 
The Second Episcopal See of the Christian world, called the 'New Rome'.The nucleus of this rite comes from the customs of the Church of Antioch: St. John Crysostom (died in 407), before to becoming a bishop of Constantinople, was a priest in Antioch and at the same time introduced into the byzantine rite the antiochean eucharistic prayer (anàphora), which still in our days keep his name. In the IX Century the Byzantine rite assumes more and more a monastic face. Great features of the monastic reform supported by men like St. Theodore Studites and St. Athanasius of Athos gave a great emphasis to the liturgical compositions and their disciples wrote several hymns for the various feasts and circumstances. The influence of the Liturgy of the monastery of St. Sabas near Jerusalem was also deeply felt and so the Byzantine rite took on an 'oriental aspect'.
The last synthesis between these elements happened around the XIV Century – a period during which the Byzantine rite rose up but not anywhere. Because of the difficult contacts between East and West, the Monastery of Grottaferrata follows the Byzantine rite but according to a more ancient type not touched by the changes which took place after the 10th.
Between the rites of Eastern and Western Christendom there are no substantial differences (with the exception of the influence operated by the different cultures) concerning the purpose of their own existence, which is to celebrate the glory of God in this world.
The Italo-Byzantine Liturgy is shared by pilgrims and tourists during the whole Liturgical year. Particularly meaningful are the Celebrations of the Holy Week.
