But the art of the East was destined to produce, at a later period, a much stronger effect, as we shall afterwards see, in Provence and Aquitaine. Besides the domical structures of Constantinople, another series of Christian buildings which had a great influence on Western architecture exists in the East. A large number of churches have been brought to light in Syria by the work of Count Melchior de Vogüé. These correspond in general features with the early churches of the West. They comprise a central nave and side aisles, separated by rows of piers, with nave arches thrown longitudinally between them. The nave is also crossed transversely with arches cast between the piers, and these are abutted by arches thrown over the side aisles. The latter, in order to resist the thrust of the central arch, require to be placed at a considerable height. The side aisles are thus rendered unnecessarily lofty, and are therefore divided into two storys with a floor which forms a gallery. The nave piers and their transverse arches are placed pretty close together in order to carry the great flag stones of which the roof is frequently composed, and which are supported upon them. Although the roof is in some cases flat, the general system of construction of these Syrian churches is very similar to what is found in the oldest churches of Southern Gaul; and which, as already mentioned, was also used in the Nymphæum at Nimes. There can be little doubt but that the Syrian structures were carefully studied by the numerous monks who visited the East in the eleventh century, while Palestine was in the hands of the Crusaders, and that they were thereby helped forward in the enterprise which was then absorbing the attention of the Western architects, viz., how to roof their churches with stone vaults. Hitherto the Western basilicas had been roofed with timber. A few examples of these early basilicas have escaped the universal destruction, and serve to indicate what the other churches which existed before the eleventh century were like. The Basse Œuvre at Beauvais is a well known specimen. It has a row of square piers on each side of the nave, separating it from the side aisles and carrying, on round arches, the upper walls containing the windows of the clerestory--the whole being covered in with a wooden roof. It was probably terminated to the east with a semicircular apse, and at the west with a narthex or porch.