The heart of the London Olympic and Paralympic Games, the 80,000-seat Olympic Stadium, shown here in a rendering, will host most of the opening and closing ceremonies as well as major track and field events. A roof covering the stadium’s perimeter will protect spectators from rain as well as support lighting and sound systems. Construction began in May on the structure, which is located south of the Olympic Park on a site surrounded on three sides by water. It will be completed some time in 2011. Shown also is the iconic Beijing Bird’s Nest stadium, which played a comparable role in 2008.