Seen from the outside, Copenhagen’s Opera House, with its bubble-faced front gently squeezed by a flat, thin roof, is akin to a giant lantern on the city’s waterfront. The front lodges a five-story foyer and another bubble, inspired by a conch, covered with golden Danish maple. The main auditorium is coated on the inside with dark maple and has three horseshoe-shaped balconies. It can seat up to 1,700 people. Besides the main stage, the opera has five side and back stages. Hydraulic machinery can change their size and enlarge the orchestra pit to hold up to 120 musicians. Maersk Mc-Kinney Moeller, one of Denmark’s wealthiest men, changed his initial sketches for a $231-million concert hall into a monument to Danish design that ended up costing nearly twice as much.