The Royal Alcázar of Seville is an exquisite palace that blends Islamic and Christian architectural styles, with a history stretching back to the 10th century. Originally a Muslim citadel, it was expanded by various dynasties before being partially rebuilt by Castilian rulers after the conquest of Seville. Today, it's a UNESCO World Heritage Site, famed for its intricate Mudejar decorations, beautiful gardens, and royal quarters that are still used by the Spanish royal family when they visit Seville.