In later-period additions to the Mosque–Cathedral of Córdoba, the basic architectural design was changed: horseshoe arches were now used for the upper row of arcades, which were now supported by five-pass arches. In sections which now supported domes, additional supporting structures were needed to bear the thrust of the cupolas. The architects solved this problem by the construction of intersecting three- or five-pass arches. The three domes spanning the vaults above the mihrab wall are constructed as ribbed vaults. Rather than meeting in the centre of the dome, the ribs intersect one another off-center, forming an eight-pointed star in the centre, which is superseded by a pendentive dome.