During the thirteenth, fourteenth, and fifteenth centuries the mosques became an aggregation of buildings, including the tomb of the founder, residences for priests, schools and hospitals. They correspond, in fact, to mediæval monasteries, and the evolution of their styles presents a certain parallel to the contemporary evolution of Gothic architecture. =Syria.=--Among the existing mosques in Syria are those of =El-Aksah= on the Temple platform at Jerusalem and of =El-Walid= in Damascus, both of which are planned like a basilica. Also on the Temple platform is the =Dome of the Rock=, misnamed the =Mosque of Omar=, the central feature of which is a circular space, crowned by a dome, which was rebuilt by Saladin in 1189. =Egypt.=--In Egypt one of the oldest is the =Mosque of Amru= in Cairo, in which the square open court is surrounded by arcades, set at right angles to the mihrab and supported by columns taken from Byzantine and Roman buildings. Somewhat similar in plan is the =Mosque of Tulun=, where, however, the arcades run parallel to the mihrab wall and the wide pointed arches are supported upon massive piers. Then follow, during the period that corresponds to the development of Gothic architecture, the =Mosque of= =Kalaoom=; that of =Sultan Hassan=, which is cruciform in plan; that of =Sultan Barbouk=, celebrated for its minarets and the beauty of the dome over the founder’s tomb; and the small but richly decorated =Mosque of Kait-Bey=. In the prayer-chamber (maksura) of the last-named appears, besides the stalactite embellishment of the mihrab, a distinctive decoration of the arches. In one case the arches are composed of voussoirs alternating in colour; in the other the alternation is still further emphasised by the interlocking shapes into which the voussoirs are cut, so that they fit together with the variety and the exactness of a Chinese puzzle.