 Crypts are often present as an underlying structure to a substantial church, and are generally a completely discrete space, but occasionally, as in some Italian churches, may be a sunken space under a raised chancel and open, via steps, to the body of the nave.Romanesque crypts have survived in many instances, such as Canterbury Cathedral, when the church itself has been rebuilt.The usual construction of a Romanesque crypt is with many short stout columns carrying groin vaults, as at Worcester Cathedral.