Porta del Perdon
Cordoba arches

Both of these structures originally served as mosques and then were transformed into grand cathedrals.

The renovators of the Sevilla building had such extensive plans that they wanted to be remembered as "mad men."1

The patron of the Cathedral at Cordoba, however, placed a cathedral in the middle of a mosque, leaving much of the original structure in tact.

Sevilla Cathedral
Cordoba Mosque and Cathedral

Religious Uses of Islamic Art and Architecture