You might dismiss them as concrete boxes, but the sheer size of America&rsquos skyscrapers will leave you gasping. The term was first used for Chicago&rsquos Home Insurance Building, a 10-storey behemoth of steel constructed in 1885. But some of the most iconic skyscrapers of today came a little later &mdash the Chrysler Building in New York was built in 1930, and the 102-floor Empire State Building, the world&rsquos tallest building for 40 years, was constructed in 1931. Chicago took the lead in 1969 with the completion of the John Hancock Centre (pic), and then in 1974 the 1,451ft Sears Tower, which remains the tallest in the US. But New York is still home to the largest number of buildings over 492ft (150m), and New Yorkers would claim that the incredibly angular Flatiron Building (built 1902) and the art deco Chrysler Building with its brick exterior are by far the prettiest skyscrapers. Take a tour organised by New York&rsquos Skyscraper Museum (www.skyscraper.org) and judge for yourself.