London Millennium Tower was one of several ideas for the site of the former Baltic Exchange at 30 St Mary Axe , City of London that had been destroyed beyond repair by a Provisional IRA bomb blast . Designed by Foster & Partners , for then owner Trafalgar House , the plan was for the building to be the tallest in Europe and the sixth tallest in the world at that time , behind the twin Petronas Towers in Malaysia , the Sears Tower ( now called the Willis Tower ) in Chicago , and the twin towers of the World Trade Center in New York . Its height was planned at 386 metres ( 1,265 ft ) , with 92 floors , which means it would have been 21st in the world today , and would be overtaken in Europe by the Federation Tower . A public viewing platform was planned for 1000 ft above ground level
bomb blast
Baltic Exchange bombing
London Millennium Tower