The origin of the word Catacombs is exceedingly obscure. Father Marchi derives it from κατὰ, down, and τύμβος, a tomb; or from κατὰ and κοιμάω, to sleep. Mommsen thinks it comes from κατὰ and _cumbo_, part of _decumbo_, to lie down. According to Schneider (_Lex. Græk._) it is derived from κατὰ and κύμβη, a boat or canoe, from the resemblance of a sarcophagus to that object. The more probable derivation seems to the present writer to be from κατὰ and κύμβος, a hollow, as if descriptive of a subterranean excavation. The name was first given in the sixth century to a limited area beneath the Church of St. Sebastian: “_Locus qui dicitur catacumbas._”--S. Greg., _Opp._, tom. ii, ep. 30. It was afterward generically applied to all subterranean places of sepulture. The earliest writers who mention those of Rome call them _cryptæ_, or crypts, or _cæmeteria_--whence our word cemetery, literally, sleeping places, from κοιμάω, to slumber. Similar excavations have been found in Syria, Asia Minor, Cyprus, Crete, the Ægean Isles, Greece, Sicily, Naples, Malta, and France. [2] These great roads for miles are lined with the sepulchral monuments of Rome’s mighty dead, majestic even in decay. But only the wealthy could be entombed in those stately mausolea, or be wrapped in those “marble cerements.” For the mass of the population _columbaria_ were provided, in whose narrow niches, like the compartments of a dove-cote--whence the name--the _terra cotta_ urns containing their ashes were placed, sometimes to the number of six thousand in a single _columbarium_. They also contain sometimes the urns of the great. [3] Ariosto, _Orlando Furioso_. [4] Aringhi, in the elegant Latin ode prefixed to his great work, exclaims, “_Sub Roma Romam quærito_”--Beneath Rome I seek the true Rome. [5] Even so accurate and philosophical a writer as the late Professor Silliman reports on their authority that the Catacombs extend twenty miles, to the port of Ostia, in one direction, and to Albano, twelve miles, in another. _Visit to Europe_, vol. i, p. 329. This is impossible, as will be shown, on account of the undulation of the ground, and the limited area of the volcanic _tufa_ in which alone they can be excavated. The number of distinct Catacombs has also been magnified to sixty; and Father Marchi estimated the aggregate length of passages to be nine hundred miles. [6] Fig. 1. [7] Fig. 30. [8] Fig. 29. [9] Primas namque fores summo tenus intrat hiatu Illustratque dies limina vestibuli.--_Peristephanon_, ii.