For the first time in nearly 40 years, New York City will be home to the country's tallest building. At a symbolic 1,776 feet, One World Trade Center will surpass Chicago's Willis Tower (formerly Sears Tower) as America's tallest building when it's completed next year. The declaration, announced today by the Council on Tall Buildings and Urban Habitat, hinged on whether the building's 409-foot mast should be classified as an antenna, which doesn't count toward height measurements, or a spire, which does. The Council concluded it was the latter. Here's how One World Trade Center measures up against the world's tallest skyscrapers (click to enlarge) and against America's.