Córdoba is a city in the southern region of Andalusia, in Spain, and is the capital of the province of Córdoba. It was an important Roman city and one of the main Islamic centers of the Middle Ages. It is known for the huge Mosque dating from 784 AD. C., with a prayer room with columns and ancient Byzantine mosaics. After becoming a Catholic church in 1236, a Renaissance-style nave was added in the 17th century.