The Moorish palace started as a fort. One of the largest Roman Catholic Cathedrals in the world used to be a mosque. The Renaissance archive contains the annals of the Spanish in the New World. All three - the Alcazar, the Seville Cathedral, and the Archivo de Indias - are UNESCO World Heritage sites. All three were built in the Mudejar style, a Muslim aesthetic that developed under Christian rule. Cruise guests can see what alchemy can happen when cultures intertwine. Walk the narrow lanes of the Jewish Quarter, the expanse of the Plaza de Espana, or the halls of the Museo de Bellas Artes. Then stop for tapas.