ROMAN ARCHITECTURE. 157 The Romans either buried or cremated their dead, both sarco- phagi (No. 6g m) and urns being sometimes found in the same tomb chamber. The bodies of the emperors during the first three cen- turies were usually burnt on magnificent pyres, from which an eagle was set free, symbolizing the escaping soul of the dead emperor. In the second century a.d. the practice of cremation became less usual ; the richer classes embalmed their dead and placed them in massive and costly sarcophagi instead of the smaller receptacle for ashes. There are five varieties of Roman tombs, as indicated on No. 52 : — (a.) Columbaria. — These were placed in subterranean vaults or caves, which are now known as catacombs, and have rows of niches in the walls resembling pigeon-holes — hence the name. Each niche was reserved for a vase containing the ashes of the deceased, with the name inscribed thereon. Sarcophagi were also placed in these tomb-chambers, some of which in addition had " loculi " or recesses for corpses, as in the Tomb of the Gens Cornelia, Rome. (b.) Monumental tombs consisted of tower-shaped blocks, square or circular, resting on a quadrangular structure and crowned with a pyramidal roof. These may be survivals of the prehistoric tumulus of earth with its base strengthened by a ring of stones. The Tomb of Ccrcilia Metella, Rome (b.c. 60), (on the Via Appia), has a podium 100 feet square, supporting a circular mass 94 feet in diameter, probably surmounted by a conical roof. The tomb-chamber was in the interior, and the whole was faced with travertine and crowned by an entablature, the frieze of which is carved with ox-skulls and festoons. The Mausoleum of Augustus, Rome (b.c. 28), was erected for himself and his heirs. Little is now left, but it is known, from descriptions of Strabo, Tacitus, and others, to have had a square basement surrounded with a portico of columns and supporting a circular mass, 220 feet in diameter, containing the mortuary chambers, the whole being capped by a mound of earth laid out in terraces and planted with cyprus and evergreen trees, and crowned with a colossal statue of Augustus. In the middle ages it was converted into a fortress, and in the eighteenth century, what remained of it, was used as a theatre. The Mausoleum of Hadrian, Rome (a.d. 135) was one of the most important of these monumental tombs. It is now the Castle of S. Angelo, and consists of a square basement about 300 feet each way and 75 feet high, supporting an immense circular tower 230 feet in diameter and 140 feet high, having a peristyle of marble columns, surmounted by a conical marble dome, as other examples. It was built of concrete, in which,
