In terms of European architecture, a crypt (from the Latin crypta and the Greek κρυπτη, kryptē) is a stone chamber or vault beneath the floor of a church usually used as a chapel or burial vault possibly containing sarcophagi, coffins or relics.
Originally crypts were typically found below the main apse of a church, such as at the Abbey of Saint-Germain en Auxerre, but were later located beneath naves and transepts as well. Occasionally churches were raised high to accommodate a crypt at the ground level, such as St Michael's Church in Hildesheim, Germany.
The famous crypt at Old St. Peter's Basilica, Rome, developed about the year 600, as a means of affording pilgrims a view of Saint Peter's tomb, which lay, according to the Roman fashion, directly below the high altar. The tomb was made accessible through an underground passageway beneath the sanctuary, where pilgrims could enter at one stair, pass by the tomb and exit, without interrupting the clerical community's service at the altar directly above.
Crypts were introduced into Frankish church building in the mid-eighth century, as a feature of its Romanization. Their popularity then spread more widely in western Europe under Charlemagne. Examples from this period are most common in the early medieval West, for example in Burgundy at Dijon and Tournus.
After the 10th century the early medieval requirements of a crypt faded, as church officials permitted relics to be held in the main level of the church. By the Gothic period crypts were rarely built, however burial vaults continued to be constructed beneath churches and referred to as crypts.
There was a trend in the 1800s of building crypts on medium to large size family estates, usually subtly placed on the edge of the grounds or more commonly incorporated into the cellar. After a change of owner these are often blocked up and the house deeds will not allow this area to be re-developed.