The Probert Encyclopaedia of Architecture

CRYPT

A crypt was originally a subterranean cell or cave, especially one constructed for sepulture, the term is now used for a chamber or compartment under a church or public building. In early Christian churches it was usually built to hold a saint's tomb or the relics of saints. A crypt is usually set apart for monumental purposes, but is sometimes used as a chapel. The crypt is a common feature of cathedrals, being always at the east end, under the chancel or apse. The largest in England is that of Canterbury Cathedral;
that of Glasgow Cathedral, formerly used as a separate church, is 'one of the most perfect pieces of architecture' in Britain.
Research Crypt