An arcade is a succession of contiguous arches, with each arch supported by a colonnade of columns or piers. Exterior arcades are designed to provide a sheltered walkway for pedestrians; they include many loggias, but here arches are not an essential element. An arcade may feature arches on both sides of the walkway. Alternatively, a blind arcade superimposes arcading against a solid wall.

The nave is the central part of a church, stretching from the main entrance or rear wall, to the transepts, or in a church without transepts, to the chancel. When a church contains side aisles, as in a basilica-type building, the strict definition of the term "nave" is restricted to the central aisle. In a broader, more colloquial sense, the nave includes all areas available for the lay worshippers, including the side-aisles and transepts. Either way, the nave is distinct from the area reserved for the choir and clergy.