Interior of the Mosque-Cathedral of Córdoba, Andalusia, Spain (© Elena Zolotova/Getty Images)

The Mosque-Cathedral of Córdoba is a chronicle of Spain's layered history. It began as a church built by the Germanic Visigoths, before being transformed into a mosque in 784 CE by Abd al-Rahman I, founder of the Umayyad Emirate of Córdoba. Its vast hypostyle hall, a space supported by rows of columns, features the famous red-and-white arches shown here. Today, it contains more than 850 columns, many reused from Roman and earlier Visigothic structures.