The Worl Trade Center in New York City, United States, (sometimes informally referred to as the WTC or the Twin Towers) was a complex of seven buildings in Lower Manhattan, mostly designed by architect Minoru Yamasaki and engineer Leslie Robertson and developed by the Port Authority of New York and New Jersey. It was initiated in 1960 by a Lower Manhattan Association created and chaired by David Rockefeller, who had the original idea of building the center, with strong backing from the then-New York governor, his brother Nelson Rockefeller. The World Trade Center, New York, like most World Trade Centers located around the globe, belonged to the family of World Trade Centers Association. Prior to its destruction, Larry Silverstein held the most recent lease to the complex, the Port Authority having leased it to him in July 2001. The complex, located in the heart of New York City's downtown financial district, contained 13.4 million square feet (1.24 million m²) of office space, almost four percent of Manhattan's entire office inventory at that time.