BBC NEWS | Special Reports | Audio slideshow: America's early skyscrapers

BBC NEWS | Special Reports | Audio slideshow: America's early skyscrapers: "At the turn of the 20th Century, New York's Woolworth Building and Chicago's Monadnock Building set a trend that transformed the skylines of US cities.

New construction methods - and the egos of America's top businessmen - meant that buildings could be higher than ever before.

Here, with the help of archive photographs, Professor David Reynolds looks at the birth of the skyscraper."