The term nave {nayv} — derived from the Latin navis ("ship") — is the main area of a church in which the congregation assembles for worship. In a longitudinal or basilican church (see basilica) the nave, flanked with arcaded aisles, extends from the narthex, or porch, to the apse, or sanctuary, housing the altar. In the huge Early Christian pilgrimage churches in Rome the nave was flanked with double aisles, all terminating in a wide transept, or transverse arm, to accommodate the clergy and to separate the nave from the apse.
In cruciform churches, typified by Chartres Cathedral, the nave, the two arms of the transept, and the choir — an extension of the nave housing the choir and the altar — form a cross. Typical Gothic nave walls consist of an arcade supporting a triforium, or second story, that in turn supports the clerestory, or third story, which is filled with windows. The nave is either vaulted (see arch and vault) or roofed with timbers.