September 8, 2006The twin towers of New York City's World Trade Center smolder (top) after terrorists flew two jetliners into them on the morning of September 11, 2001. The towers would soon collapse, killing about 2,750 people and making the Empire State Building (bottom) the tallest building in the city for the first time since 1972.
By 2011 Freedom Tower, built on the site of the former trade center, is expected to surpass the 1931 landmark in height, if not in the hearts of New Yorkers.
You could win $20,000 to put it into action. Take part in the Green Effect, a new initiative from SunChips and National Geographic to inspire people to take small steps for big change.