GROTTAFERRATA, a village of Italy, province of Rome, 13 m. southeast from Rome by electric tramway, and 2 z m. south of Frascati, I,o8o ft. above sea-level, in the Alban Hills. The name (in its Latin form, Crypta ferrata, i.e., the crypt with an iron grille) probably comes from an older building, perhaps an oratory, perhaps originally an ancient tomb, which served as the foundation for the campanile. Pop. (1931) 4,481. It is noticeable for the Greek monastery of Basilians founded by S. Nilus in 1002 under the Emperor Otho III., which occupies the site of a large Roman ville. It was fortified (end 15th century) by Cardinal Giuliano della Rovere (afterwards Pope Julius II.), whose arms may be seen about it. The church with its fine campanile belongs to the 12th century, and the original portal, with a mosaic over it, is still preserved, as is also the mosaic of the apse. The chapel of S. Nilus contains frescoes by Domenico Zampieri (Domenichino) of 161o, illustrating the life of the saint. The abbot's palace has a fine Renaissance portico, and contains local antiquities. An omophor ion (see PALLIUM) of the i 1th or 12th century, with scenes from the Gospel in needlework, and a chalice of the 15th century with enamels are among its treasures. The library contains valuable MSS., among them one from the hand of S. Nilus (965); and a palaeographical school, for the copying of MSS. in the ancient style, is maintained.
See T. Ashby in Papers of the British School at Rome, v. (London, 191o), 228 sqq.; F. Tomassetti, Campagna Romana, iv. (Rome, 1926), sqq. (T. A.)