A crossing, in ecclesiastical architecture, is the junction of the four arms of a cruciform (cross-shaped) church.
[1] In a typically oriented church (especially of Romanesque and Gothic styles), the crossing gives access to the nave on the west, the transept arms on the north and south, and the choir, as the first part of the chancel, on the east.
Because the crossing is open on four sides, the weight of the tower or dome rests heavily on the corners; a stable construction thus required great skill on the part of the builders.
[3] Sacrist Alan of Walsingham's octagon, built between 1322 and 1328 after the collapse of Ely's nave crossing on 22 February 1322, is the "... greatest individual achievement of architectural genius at Ely Cathedral" according to architectural historian Nikolaus Pevsner.
[5] The term is also occasionally used for secular buildings of a cruciform plan, for instance The Crystal Palace in London.