In 1004 St. Nilo the Younger, hegumen (head of the Abbey) of the Greek Byzantine monks, escaped from Calabria because of the Saracen raids, and founded the Abbey on spacious grounds given to him by Count Gregory I of Tusculum. The Abbey, also known as the Abbey of Santa Maria di Grottaferrata, was consecrated in 1024 by Pope John XIX.
The strong link between the monastery and the Counts of Tusculum meant that, in 1037, Benedict IX granted it the rights to the territory of Albano and called the abbot Bartolomeo as a counsellor. In the twelfth century, Callistus II declared the abbey subject solely to the Holy See and free from the jurisdiction of the bishop. The monastery came to own vast land ranging from Albano to the Labicana.
In 1379, during the schism of the West, the monks abandoned the abbey again, under the protection of the Caetani lords of Marino. In 1462, Pius II interrupted the series of perpetual abbots and gave the abbey in commenda (contract of work) to Cardinal Bessarion, who was followed by Giuliano della Rovere. Cardinal della Rovere built the walls with a crenellated parapet walk, with cylindrical towers on three sides, and the palace of the Commanda, probably designed by Giuliano da Sangallo, or perhaps by Bramante. The access bridge to the Abbey brings you to the courtyard with a large statue of St. Nile and the Sangallo portico.
From 1626 to 1738 the Abbey was ruled by the Barberini and was then despoiled by Napoleon’s troops. The abbey was then run by the Basilian religious sect who follow the Byzantine rites of the Church of Constantinople. The Monastery, in fact, was founded about 50 years before the Eastern Schism but Catholics can participate in the Byzantine rites of San Nilo and receive the sacraments.
The abbey has an important library which houses more than a thousand ancient manuscripts and about 50,000 volumes of great value, some dating back to the years of the founding of the Abbey and having belonged to San Nilo.
Since 1931, the Abbey has had a famous Laboratory of Ancient Book Restoration where it has restored the famous “Atlantic Codex” by Leonardo da Vinci and many manuscripts recovered from the flood in Florence of 1966. The Abbey is also home to an archaeological museum with a rich collection of archaeological finds.