Each door has a blind horseshoe arch inscribed in an alfiz above an arched lintel and are framed with niches and blind arcades that often exhibit such complex arch types as interlaced or polylobed arches.
Constructed on a simple hypostyle plan, ‛Abd al-Rahman’s mosque of 785 consisted of 11 aisles of 12 bays that, like the Great Mosque at Damascus, ran perpendicular to a walled court. Each bay was defined by a set of two-tiered horseshoe arches with alternating red brick and white stone voussoirs, which were later coloured. It was enlarged by building programs until 988. In 1236 Ferdinand III of Castile and a number of bishops purified the Great Mosque for Christian worship, consecrating it as a cathedral dedicated to S María. The building was initially altered only by the creation of St. Clement’s Chapel and by a number of Christian burials. Large-scale alterations began with the Capilla Real (late 13th century-early 14th), a pantheon for the kings of Castile. It was altered drastically by the construction of a vast cathedral at its centre in 1523. A UNESCO World Heritage Site.