The Great Mosque of Córdoba was originally built by the Visigoths as the Catholic Basilica of Saint Vincent of Lérins. When Muslims conquered Spain in 711, the church was first divided into Muslim and Christian halves. This sharing arrangement of the site lasted until 784, when the Christian half was purchased by the Amir 'Abdur-Rahman I, who then proceeded to demolish the entire structure and build the grand mosque of Cordoba on its ground. Córdoba returned to Christian rule in 1236 during the Reconquista, and the building was converted to a Roman Catholic church, culminating in the insertion of a Renaissance cathedral nave in the 16th century.

 From Wikipedia