what was on top of the twin towers
World Trade Center (1973–2001) Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communication antenna on top of each building.[42] Only 1Â WTC (north tower) actually had an antenna fitted; it was added in 1978.[45] The truss system consisted of six trusses along the long axis of the core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.[42]
Alonso Álvarez de Pineda
30 St Mary Axe After plans to build the 92-storey Millennium Tower were dropped, 30 St Mary Axe was designed by Norman Foster and Arup Group.[12] It was erected by Skanska, with construction commencing in 2001.[3]
One World Trade Center One World Trade Center (also known as 1 World Trade Center, 1 WTC or Freedom Tower[15]) is the main building of the rebuilt World Trade Center complex in Lower Manhattan, New York City. It is the tallest building in the Western Hemisphere, and the sixth-tallest in the world. The supertall structure has the same name as the North Tower of the original World Trade Center, which was destroyed in the terrorist attacks of September 11, 2001. The new skyscraper stands on the northwest corner of the 16-acre (6.5 ha) World Trade Center site, on the site of the original 6 World Trade Center. The building is bounded by West Street to the west, Vesey Street to the north, Fulton Street to the south, and Washington Street to the east.