View looking up at later ceiling; A standard type of basilica and a standard type of baptistery evolved and spread throughout northern Italy, and from North Africa to southern Spain and Gaul. The standard type of basilica was meant to hold a congregation of between 800 and 1400. It consists of a nave flanked by aisles and terminating in a semicircular, sometimes rectangular, apse; a narthex and atrium sometimes feature at the west end. This standard type of basilica is known as early as the late 4th-century church of S Ambrogio at Milan, which has three aisles and a semicircular eastern apse, a plan that became widespread in northern Italy in the 5th century. After ca. 380 examples of the type at Rome include S Clemente. The schola cantorum...