Construction on the Olympic Stadium began in 2007. At $785 million, its building cost was less than half the price of today's top-level football stadiums in New York and Texas. The result was a structure using 10,000 tons of steel. In contrast, the Bird's Nest used 42,000 tons. Slated to seat 80,000 spectators during the games and to scale back to just 25,000 for its post-games life as a sports and community events venue, the stadium will be only the third-largest stadium in Britain. Its base level, which will be its only level after the Games, is constructed of low-carbon-dioxide concrete--"low" meaning it contains 40 percent less than regular concrete. 800,000 tonnes (that's 881,849 American, or "short," tons) of dirt was hauled out of the location's ground, to a depth of 20 meters.