The Mezquita (Spanish for 'mosque'), is a Roman Catholic cathedral in Córdoba, Spain that was at one time the second largest mosque in the world. The construction of the Mezquita (originally the Aljama Mosque) lasted for over two centuries, starting in 784 A.D. under the supervision of the first Muslim Amir Abd ar-Rahman I, who used it as an adjunct to his palace and named it to honour his wife.

The building is most notable for its giant arches, with over 1,000 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. The 'poly-lobed' arches were a new introduction to architecture, and helped support the tremendous weight of the higher ceilings. Besides these horseshoe-topped arches, the Mezquita also features richly gilded prayer niches. A centrally located honey-combed dome has beautiful blue tiles decorated with stars. The mihrab is a masterpiece of architectural art, with geometric and flowing designs of plants. The Mezquita reached its current dimensions in 987 with the completion of the outer naves and orange tree courtyard.

The year (1236) that Cordoba was recaptured from the Moors, by King Ferdinand III of Castile and rejoined Christendom, the mosque was reconsecrated a Christian church.