Crypt (Gr. κρύπτη, a concealed place; Lat. crypta; Fr. crypte).
I. Among the ancient Greeks and Romans a crypt was primarily a long, narrow gallery, above the level of the ground, surrounding a court-yard, and having walls on both of its sides, with windows in the wall facing the court. These crypts had often a portico lining them or running between them and the open court. They served as a place of promenade during the hot or wet weather, and were finally so extensively used that they were even built for the officers near the Praetorian camps in Rome. Crypts similar in construction and location were built for storing wines, vegetables, and other articles, like the modern subterranean cellar. When all the windows were closed they were dark and cool, and hence the word was applied even by the ancients to any dark and long chamber or passage, as the dark stables where horses were kept under the amphi-theater, the cloaca maxima at Rome, the tunnel at Naples, and to a grotto where Quartilla offered sacrifice.
II. The word crypt was applied by the early Christians to those subterranean burial-places which were afterwards called Catacombs (q.v.). The term was later limited to the larger chambers in the Catacombs where one or more martyrs were buried. These crypts were larger than the other rooms in the Catacombs, and were often ornamented, and devoted to divine worship. For this purpose they were double, one part serving for the men and the other for the women, with small antechambers for the catechumens. Some of these crypts had openings into the fields above.
III. When persecution ceased, and Christians built church edifices above ground, the custom was adopted of placing the remains of martyrs — later of archbishop, bishops, abbots, and other high church officials — in crypts under the intersection of the cross in the plan of the church. In the Basilican period of architecture these crypts were often called by the name confessio. In. the Romanesque period the name crypt was resumed. In the churches of this period, the crypt extended under the high altar and back under the entire choir or apsis, sometimes even including the space under the transept. This crypt formed almost a separate church, and caused the floor above it of the main body of the church to be raised higher than that of the nave, to which the audience had access. Churches founded in the latter part of the Romanesque period, and thereafter, had no crypts. The reason of their disappearance from church architecture is not well understood. — Liibke, Geschichte der Architektur; Rich, Dictionary of Greek and Roman Antiquities.