"What has 200 elevators, 1,200 restrooms, 40,000 doorknobs, 200,000 lighting fixtures, 7 million square feet of accoustical tile ceilings, more structural steel than the Verrazno Narrows Bridge -- and was built for a final cost of over one billion 1970s dollars? That's right, the World Trade Center, built by the Port Authority of New York and New Jersey, as part of a plan conceived by the Rockefeller-led Downtown-Lower Manhattan Association to shore up Downtown's fortunes.

"Now, every weekday, 50,000 people come to work in 12 million square feet of office, hotel, and commercial space in the seven buildings in this city-within-a-city, where they are joined by 80,000 visitors passing through an enormous interior shopping mall below the 5-acre Austin J. Tobin Plaza.

"The Trace Center welcomes visitors from around the world to a splendid observatory, the Top of the World on the 107th floor of Two World Trade Center. As many as 10,000 visitors in a single day ride the non-stop express elevators -- from the lobby to the 107th floor in 82 seconds -- to take in the spectacular views of the city and its surroundings.

"Building the world's tallest buildings involved extraordinary feats of engineering. The Trade Center's superblock site replaced 12 Downtown blocks originally laid out on landfill reclaimed from the Hudson River.

"Bedrock lay 70 feet below the watery ground, making excavation nearly impossible. The Trade Center's engineers imported a 'slurry trench' technology from Italy that eabled them to sink a reinforced concrete perimeter wallsix stories down to bedrock, and then excavate a 500,000-square-foot concrete-lined hole dubbed 'the bathtub' -- exposing the enclosed tubes of the PATH commuter trains whose service continued uninterrupted.

"The 1.2 million cubic yards of excavated rubble were dumped into the Hudson River to create yet more landfill -- the core of the 23.5 acres now underlying Battery City Park."