The Mosque of Cordoba in Andalucia, Spain, was originally the location of the church, which was bought by the Muslim emir Abd ar-Rehman I and later transformed into one of the largest mosques in the world, whose work began in 784 CE. Cordoba has become one of the most advanced cities in the world, as well as an excellent cultural, political and economic center, and the mosque has become an excellent training center.
The building is most famous for its gigantic arches, with over 1000 columns of jasper, onyx, marble and granite; double arches, which were a new architectural feature, and a rich and sophisticated design, making it one of the most beautiful mosques that have ever existed.
In 1236 CE, Cordoba was seized from Muslims by King Ferdinand III, and the mosque was re-consecrated as a Christian church, the most significant change of which was the construction of the Renaissance cathedral nave in the center of the building (see above).
Sources: YouTube and Wikipedia