It was a Roman settlement on the right bank of the Guadalquivir, taken over by the Visigoths, followed by the Muslim conquests in the eighth century and later becoming the capital of the Umayyad Caliphate of Córdoba. During these Muslim periods, Córdoba was transformed into a world leading center of education and learning, producing figures such as Averroes, Ibn Hazm, and Al-Zahrawi, and by the 10th century it had grown to be the second-largest city in Europe. Following the Christian conquest in 1236, it became part of the Crown of Castile.