Casa Palacio Castelar, an ultra-chic example of 19th century opulence, is the new setting for the 12-room Mercer Sevilla, a triumphant fusion of vintage and vanguard. The style mash-up begins in the marble courtyard patio where a magnificent marble staircase, elegant, pewter-toned Maria Luisa Restaurant, central fountain, and skylight glass paneling combine seamlessly with the cutting-edge artwork. An arched passageway leads to the autumn-hued Fizz Bar, which serves creative concoctions from award-wining barman Diego Cabrera in an intimate, urban setting. In the rooms, color tones are more earthbound—taking a backseat to intricate silkscreen room dividers and state-of-the-art leather furnishings. The rooftop terrace and wood-paneled plunge pool offer respite, day or night.