Grottaferrata is a small town situated on the lower slopes of the Alban Hills, 20 km south east of Rome. The Abbey of Santa Maria di Grottaferrata (also known as Abbazia di San Nilo) is one of the main monuments of Lazio. The monastery has several courts, which lead to the famous portico designed by Antonio da Sangallo the Younger, with an arcade of nine bays supported by slender columns with elegant Renaissance capitals. Of the abbey church consecrated by John XIX in 1024, little can be seen in the interior except the mosaics in the narthex and over the triumphal arch, the medieval structures having been covered or destroyed during the “restorations” of various abbots in commendam.
Some fragmentary 13th century frescoes were revealed in a partial restoration of the church in 1904 to commemorate its novecentennial, when it was made a Roman basilica. The mosaics portray the Twelve Apostles sitting beside an empty throne, evoking Christ’s Ascent to Heaven. Domenichino’s frescoes, commissioned by Cardinal Odoardo Farnese in 1608, can be seen in the chapel of St Nilus. Annibale Carracci executed the altarpiece of the Madonna with Child with St Nilus and St Bartholomew.
The library of the Abbey, which contains some 50,000 volumes, has a paper conservation Laboratorio di Restauro, which was entrusted with the conservation of Leonardo’s Codex Atlanticus from the Biblioteca Ambrosiana; the library houses writings of St Nilus and his pupils and a rare copy of Alvise Cadamosto’s collected travel accounts, printed in the early sixteenth century. Pope Benedict IX died and was buried in this abbey.