undercroft

Undercroft, un′dėr-kroft, n. a vault under the choir or chancel of a church: a vault or secret walk underground.

The ancient history of this undercroft is unknown, and merely a matter for conjecture.

The canopy is gone, but fragments of it are in the undercroft of the chapter-house.

One, which is generally called a lantern, was till lately hung in the undercroft.

Two heavy wooden doors at the entrance leave no doubt as to the purpose for which the undercroft was built.