transept (trănˈsĕptˌ) [key], term applied to the transverse portion of a building cutting its main axis at right angles or to each arm of such a portion. Transepts are found chiefly in churches, where, extending north and south from the main body, they create a cruciform plan. They may consist of a central portion as wide as the church nave, with two side aisles or with only one. The rectangular or square space formed by the intersection with the nave is termed the crossing. The cross-hall of vaulted Roman basilicas probably inspired the builders of early Christian churches. This position of the transept remained unchanged. In Romanesque churches the transept became universal, while the development of vaulting unified it organically with the body of the building. Its height equaled that of the nave, while the heavy piers of the crossing frequently supported an exterior dome or tower. Transepts furnished additional space for altars and chapels. In some French Gothic cathedrals transepts projected only slightly from the building. Their ends, however, were richly emphasized externally, with sculptured portals and rose windows, as at Chartres and Amiens, or with a tower, as at Le Mans. In England the transepts, furnishing practically the only opportunity for altars, were long and of deep projection. The need for still more space resulted in the frequent provision of a second and minor transept farther east, behind the choir, as at Salisbury.