The excavations have been carried out by voluntary subscriptions, and visitors are expected to make a donation in furtherance of this object. A book for the names and amounts will be found in the sacristy. UPPER CHURCH. The usual entrance from the street is by a side door, but the proper entrance is by a gate with a Gothic canopy of the thirteenth century, which originally formed part of the earlier basilica, thence through the atrium and quadriporticus, the only perfect ones of Rome. The aisles are formed by sixteen ancient pillars of different materials and orders. In the middle of the nave is the choir (514-22) from the earlier basilica; on each side are the ambones. The walls are adorned with Christian emblems, and a monogram of Agios--Holy. The nave is separated from the high altar by an ancient marble screen. Behind is the presbytery, which contains an ancient episcopal chair, with the name of Anastasius, who was titular cardinal of the church in 1108, engraved upon it. Upon the vault is a mosaic of 1297, representing Christ on the Cross, from the foot of which issue the four rivers of Paradise, with shepherds and their flocks, and peacocks. On the face of the arch is a mosaic of the time of Paschal II.--our Saviour; on either side two angels, and the emblems of the four evangelists; below are S. Peter, S. Clement, Jeremiah, S. Paul, S. Lawrence, and Isaiah; at the bottom, Bethlehem and Jerusalem, with the mystic lamb and sheep. In the chapel, on the right, the statue of S. John is by Simone; on the left, the picture of the Virgin is by Conca. The monument composed of two half-columns, with basket-work capitals and foliage reliefs, is to Cardinal Venerio, who died in 1479. _To the left on entering_, in the Chapel of the Passion, are the interesting frescoes by Masaccio (much spoilt by restoration), representing the Crucifixion, &c., and events from the lives of SS. Clement and Catherine. _Outside_ the arch, the Annunciation, and S. Christopher carrying the infant Christ over a stream; _within_, S. Catherine forced to Idolatry, Instruction of the King's Daughter in Prison, Dispute with the Doctors, Miracle of her Deliverance, Martyrdom. Opposite is the history of S. Clement. _Proceeding into the sacristy_, which is adorned with paintings of various interesting parts of the more ancient buildings, _a wide stair conducts to the_ LOWER CHURCH, founded on the site of S. Clement's house, it is supposed, in the time of Constantine. S. Jerome says: "The church built to S. Clement keeps the memory of his name to this day." So that it must have been erected before A.D. 400.