The Early Christian basilica
A tall nave lit by a clerestory, lower aisles, an apse at the end and an open timber roof; an atrium and narthex before the doors.
The rules it illustrates
Light the nave from above the aisles. Raise the central nave above the lean-to roofs of the aisles and pierce the upper walls with a row of windows, the clerestory, so that the middle of a wide hall is lit from high on both sides.
Span the nave in timber. Cover a wide nave with triangulated timber trusses rather than a vault: their tie-beams take the outward thrust, so the walls need only carry weight and may stand on slender columns.
From the atrium to the apse. Order the church as a single path: a colonnaded atrium, a narthex, the long nave drawn toward the altar, and the apse framed by a triumphal arch at the end of the axis.
The forum basilica. Make a basilica between a third and a half as broad as it is long; make each aisle a third of the width of the central space, and the columns as high as the aisles are broad.
Enclosure, gateway, forecourt, fountain. Wall the whole precinct; open a great gateway toward the approach; before the church set a court open to the sky with porticoes on four sides and fountains in it, where those who enter may wash before they go in by the three doors.
Where it appears in the book
In the styles Early Christian.
In the chapters Walls and Openings, Byzantium and the Early Church.