7 World Trade Center, located across Vesey Street from the Twin Towers and other World Trade Center buildings, was built in the early-mid 1980s, on top of a two-story Con Edison substation. 7 World Trade Center collapsed at 5:20 pm on September 11, 2001, after suffering extensive damage from fires and falling debris from the collapse of the World Trade Center towers. Soon after September 11, 2001, FEMA initiated a preliminary study into the collapse of the World Trade Center buildings, including 7 World Trade Center. This was followed up by a more extensive investigation by NIST, which is still ongoing. The original Seven World Trade Center was finished in 1987. The original structure had 47 floors and was 570 feet (174 m) tall.[1] Construction began in 1984; in March 1987, the building opened, to become the seventh structure of the World Trade Center. The building was built on top of a Con Edison substation dating from 1967. The substation had a caisson foundation designed to carry the weight of a future building on the site. The final design for 7 World Trade Center was for a building covering a significantly larger footprint than originally planned when the substation was built. Between floors 5 and 7, the building had a system of transfer trusses and girders to transfer load to the smaller-sized foundation. The spray-on fireproofing for structural steel elements was gypsum-based Monokote, which had a 2-hour rating for steel beams, girders and truss, and 3 hour rating for columns. Each floor had 47,000 square feet (4,366 m²) of rentable office space, which made the building's floor plans considerably larger than most other office buildings in the city. In all, 7 World Trade Center had 1,868,000 square feet (174,000 m²) of office space. The building was clad in red exterior masonry. A pedestrian bridge connected it to the main World Trade Center complex, to the south, across Vesey Street. Emery Roth & Sons designed the building.
