Wembley Stadium, London

With 90,000 seats, the new Wembley Stadium will be the largest soccer arena in the world. The signature 98.3-foot-tall twin towers of the original Wembley, built for the British Empire Exhibition in 1924, are being replaced with a dramatic 436-foot arch that will support 5,000 tons of the 7,000-ton movable roof. This structural solution eliminates the need for pillars that could obscure visitors' views. (With a span of 315 meters, the arch will be the longest single-span roof structure in the world and will be visible from all parts of London.)