Basilica: Architectonic type of church. It is a rectangular -in its ground plan- chamber divided by colonnades in three or more aisles. The architectural type of basilica was used by the Christians from the 4th century as a place of worship. The eastern part tapers into a semicylindrical niche, the apse, which is intended for the clergy, while at the west lies the narthex for the catechumens.