The original World Trade Center was a large complex of seven buildings in Lower Manhattan, New York City, United States. It opened on April 4, 1973 and was destroyed in 2001 during the September 11 attacks. At the time of their completion, the Twin Towers — the original 1 World Trade Center, at 1,368 feet (417 m); and 2 World Trade Center, at 1,362 feet (415.1 m) — were the tallest buildings in the world. Other buildings in the complex included the Marriott World Trade Center, 4 WTC, 5 WTC, 6 WTC, and 7 WTC. The complex was located in New York City's Financial District and contained 13,400,000 square feet (1,240,000 m2) of office space.