The most frequently recurring symbol is the seven-branched candelabrum. Two chambers are enriched with decorative paintings, in which, contrary to the Mosaic law, figures of animals also are depicted. A sarcophagus here still retains traces of gilding.
The Catacombs of SS. Peter and Marcellinus, near the Torre. Pignattara (p. 438), are among the most extensive. The ceiling of a lofty chapel bears an Enthroned Chrit,s with St. Paul on the right and St. Peter on the left, with four saints below, quite in the style of the earliest mosaics. Other frescoes, such as two scenes of family feasts, belong to the 3rd century.
The Catacombs of St. Pontianus, situated in the Vigna di San Michele ½ M. from the Porta Portese (p. 423; to the right before the Strada Ai Monteverde), are excavated in the breccia of Monte Verde. At the foot of a staircase descending into it is a basin with water, serving as a baptistery. On the wall beyond is the Baptism of Christ (with a stag near the Jordan), above a large cross in the later style. Above the staircase are two large medallions with heads of Christ of the 6th and 9th(?) centuries.
The Oratorio of Sant' Alessandro, 6 M. from the Porta Pia (p. 437), is a long, half-subterranean building of very poor masonry. According to an inscription on the altar, this was the tomb of a certain Alexander, perhaps the bishop of that name. The oratory is surrounded with lofty passages still containing undisturbed tombs.
Catacombs of St. Generosa, see p. 489.
The well-wooded Alban Mountains (Monti Albani or Laziali) consist of an isolated group of basaltic formation (lava and tufa), gradually rising from a plain overlaid with volcanic ashes and forming an imposing pyramid, which culminates in Monte Cavo (3115 ft.) and the Punta Faette (3135 ft.). In the middle of the outer cone lies a wide basin-shaped depression, which is enclosed on the E. by a continuous wall of rock, while to the W. it includes two smaller basins filled with water (Lago d'Albano, Lago di Nemi) besides the now dry Valle Aricciana and Laghetto di Turno. It was formerly supposed that these represented a central and three lateral craters; but they were more probably formed by subsidences occurring during a relapse after the chief period of volcanic activity. When this activity was resumed the Monte Cave, which has its crater in the Campo di Annibale, was formed above the ancient outlet. Long streams of lava were poured out towards Rome, towards Velletri, and towards the N_; these may be recognized in the hilly ridges, which are now intersected by the railways. The tufa rock occurs in several varieties, one of the most widespread of which is that called peperino, whose variegated appearance is due to the minerals it contains, and to the baked and fired fragments of limestone and clay. The presence of these ingredients indicates very violent explosions, which shattered the rocks below the volcanoes, and expelled masses of the fragments. Within the historic period the volcano has been extinct, but the earthquakes which occasionally occur at Albano, Nemi, and Rocca di Papa recall the fact that the whole mountain mass is of recent origin. Its height and its isolated situation make it a healthy district, abounding in springs and surrounded by luxuriant cultivation. Alban wine was famous even in antiquity. On the N. slope of the group lies Frascati, and on the S.W. slope Albano, both of which have been surrounded since the most ancient times with the country-houses of wealthy Romans. — The natural beauty of the scenery here has always made these mountains a favourite resort of visitors from Rome. The inhabitants have preserved many of their