<P> The main hall of the mosque was used for a variety of purposes . It served as a central Prayer hall for personal devotion, the five daily Muslim prayers and the special Friday prayers . It also would have served as a hall for teaching and for Sharia Law cases during the rule of Abd al - Rahman & his successors . </P> <P> The Great Mosque of Córdoba exhibited features, and an architectural appearance, similar to the Great Mosque of Damascus, therefore it is evident that it was used as a model by Abd al - Rahman for the creation of the Great Mosque in Córdoba . </P> <P> The building is most notable for its arcaded hypostyle hall, with 856 columns of jasper, onyx, marble, and granite . These were made from pieces of the Roman temple which had occupied the site previously, as well as other destroyed Roman buildings, such as the Mérida amphitheatre . The double arches were a new introduction to architecture, permitting higher ceilings than would otherwise be possible with relatively low columns . The double arches consist of a lower horseshoe arch and an upper semi-circular arch . The famous alternating red and white voussoirs of the arches were inspired by those in the Dome of the Rock. and also resemble those of the Aachen Cathedral, which were built almost at the same time . Horseshoe arches were known in the Iberian Peninsula since late Antiquity, as can be seen on the 3rd - century "Estela de los Flavios", now in the arqueological museum of León . A centrally located honey - combed dome has blue tiles decorated with stars . </P> <P> The edifice also has a richly gilded prayer niche or mihrab . The mihrab is a masterpiece of architectural art, with geometric and flowing designs of plants . Other prominent features were: an open court (sahn) surrounded by arcades, screens of wood, minarets, colourful mosaics, and windows of coloured glass . The walls of the mosque had Quranic inscriptions written on them . As many adherents of Islam reject sculptural or pictorial representations of people or of God within religious contexts, all decoration of the cathedral is accomplished through tile work, calligraphy and architectural forms . </P>

What is the style of arch found at the great mosque at cordoba