The interest of these buildings lies not so much in their venerable antiquity as in the fact that the arrangements of all Christian churches in Western Europe down to the Reformation, and of very many since, are directly derived from these originals. If the reader will refer to the description of a Gothic cathedral in the companion volume of this series,[28] it will not be difficult for him to trace the correspondence between its plan and its general structure and those of the primitive basilica. The atrium no longer forms the access to a cathedral, but it still survives in the cloister, though in a changed position. The narthex or porch is still more or less traceable in the great western portals, and in a kind of separation which often, but not always, exists between the westernmost bay of a cathedral and the rest of the structure. The division into nave and aisles remains, and in very large churches and cathedrals there are double aisles, as there were in the largest basilicas. The nave roof is still higher than the aisles--the arcade, in two stories, survives in the usual arcade and triforium; the windows placed high in the nave are the present clerestory. The apsidal termination of the central avenue is still retained in almost all Continental architecture, though in Great Britain, from an early date, it was abandoned for a square east end; but square-ended or apsidal, a recess with a raised floor and a conspicuous arch, marking it off from the nave, always occupies this end of the church; and the under church, or crypt, is commonly, though not always, met with. The enclosure for the choir has, generally speaking, been moved farther east than it was in the basilica churches; though in Westminster Abbey, and in most Spanish cathedrals, we have examples of its occupying a position closely analogous to that of the corresponding enclosure at the basilica of San Clemente. The cross passage to which we have referred as having existed in the old basilica of St. Peter, and many others, is the original of the transept which in later churches has been made more conspicuous than it was in the basilica by being lengthened so as to project beyond the side walls of the church, and by being moved more westward. Lastly, the two ambos, or pulpits, survive in two senses. They are represented by the reading desk and the pulpit, and their situation and purpose are continued in the epistle and gospel sides of the choir.