On September 11, 2001, terrorist hijackers steered two commercial jets into the World Trade Center's 110-story towers, demolishing them and five outlying buildings and killing nearly 3,000 people. Dubbed Ground Zero, the fenced-in 16-acre work site that emerged from the rubble has come to symbolize the personal and historical impact of the attack. In an attempt to grasp the reality of the destruction, to pray, or simply to witness history, visitors come to glimpse the site, clustering at the two-story see-though fence surrounding it. Temporary panels listing the names of those who died in the attacks and recounting the history of the twin towers have been mounted along the fence on the west side of Church Street and the north side of Liberty Street.

The World Trade Center (WTC) was a seven-building, 12-million-square-foot complex resembling a miniature city, with more than 430 companies from 28 countries engaged in a wide variety of commercial activities, including banking and finance, insurance, transportation, import and export, customs brokerage, trade associations, and representation of foreign governments. The daytime population of the WTC included 50,000 employees and 100,000 business and leisure visitors. Underground was a mall with nearly 100 stores and restaurants and a network of subway and other train stations. The twin towers were New York's two tallest buildings, the fourth tallest in the world after Kuala Lumpur's Petronas Towers, Shanghai's Jin Mao Building, and the Sears Tower in Chicago. The two 1,350-foot towers, designed by Minoru Yamasaki and opened in 1973, were more engineering marvel than architectural masterpiece. To some they were an unmitigated design fiasco; to others their brutalist design and sheer magnitude gave them the beauty of modern sculpture, and at night when they were lighted from within, they were indeed beautiful strokes on the Manhattan skyline. Whether they were admired or reviled, the towers endured as a powerful symbol of American ingenuity, success, and dominance in the world marketplace. COST: free. Subway: R, W to Cortlandt St.