Until last fall, Seville lacked a luxury hotel worthy of the city’s world-class architecture. The Mercer Sevilla changes that. The seductive 12-room retreat occupies a meticulously restored 19th-century palacio. White-on-white guest rooms mix original wood floors with modern furnishings. The rooftop pool’s deck is ideal for a siesta; in the cocktail bar, the drinks were dreamed up by noted Seville bartender Diego Cabrera.