The Past and Future of Skyscrapers

From humble beginnings a little more than a century ago, skyscrapers have come to dominate the the skylines of great cities in America and many other parts of the world. The collapse of the World Trade Center towers has raised new questions about skyscrapers. David Andrew is an architectural historian and he talks about skyscraper structure and history, as well as the place inhabited in our imagination, by the tallest of buildings.