New York has two separate concentrations of high-rise buildings: Midtown Manhattan and Lower Manhattan, each with its own uniquely recognizable skyline. Midtown Manhattan, the largest central business district in the world, is home to such notable buildings as the Empire State Building, the Chrysler Building, Citigroup Center and Rockefeller Center. Lower Manhattan comprises the third largest central business district in the United States (after Midtown and Chicago's Loop). Lower Manhattan was characterized by the omnipresence of the Twin Towers of the World Trade Center from its completion in 1973 until its destruction in the September 11 attacks, 2001.
Today Lower Manhattan is undergoing a rapid reconstruction, to include the new One World Trade Center. The Downtown skyline will also soon get notable additions from such architects as Santiago Calatrava and Frank Gehry. Goldman Sachs is building a 225 meter tall, 43 floor building across the street from the World Trade Center site.