Roofs of basilicas were generally trussed: beneath a double-sloping roof, an extra story was added to the nave by building walls above the supports; these walls were pierced by windows permitting direct illumination of the nave, hence the name clerestory. The arrangement of the trusses is clear from the imprint of beams in the walls, where they are preserved e.g., in Syria and Asia Minor by the 6th-c. trusses still in loco in the Church of St. Catherine on Mt. Sinai and by graphic evidence, like the cross sections of Old St. Peter’s at Rome. Taipei Map Tourist Attractions In these we can see that each pair of side aisles was covered by one single-sloping roof, but in other five-aisled churches a clerestory above the outer colonnades is possible: in such cases we may suppose that the ceiling was masked e.g., when texts allude, as at S. Apollinare Nuovo, Ravenna, to the gilded sky. The ceiling was sometimes, in N Africa and Spain, made of terracotta slabs forming coffers, a great many examples of which have been found.
The roof itself was normally made of tiles arranged in the Roman style, flat tiles with their edges covered by semitubular tiles, terminating toward the outer margin in antefixes, sometimes decorated with relief motifs known in Africa and Gaul. Some prestigious buildings were, like some temples, covered with lead or bronze hence the allusion to golden roofs. It is practically certain that, in regions where timber was rare and the climate suitable e.g., N Africa, some parts were covered with a terrace of masonry or terracotta bricks. We also know in Syria, and probably in the Negev, a series of basilicas covered by great stone slabs. On the short sides of the hall, the roof of the nave ended in a triangular pediment which could be emphasized by acroteria at the corners and center, as in temples, or by a cross. Above the side aisles some churches had galleries open toward the nave and accessible by inside or outside stairs see below: matroneum. 2. Orientation.
The position of the apse determined the orientation of the whole building. On this point we find great regional variations. At Rome and in proconsular Africa Byzacena and Tripolitania Tunisia and part of Libya many of the oldest buildings have the apse at the west. Orientation seems to have been imposed on N Africa in the Byzantine period, at which time various churches saw their liturgical arrangements reversed. This was sometimes the cause of a second apse being built: see below. Elsewhere eastern orientation is far more frequent and is the rule in the E Mediterranean, but in Cyrenaica an intermediate zone basilicas facing west are as numerous as those facing east, for no apparent reason. Finally there are anomalous orientations, e.g., north-south, where buildings were adapted to topographical situations.