Must have a head for heights! London's Tower Bridge unveils £1m glass walkway with dizzying views 140ft above River Thames

From nearly 140ft above the Thames, visitors can watch the buzz of activity below as buses and pedestrians cross the historic bridge, boats sail under it and bascules are raised beneath their feet. While testing visitors' nerves the floor offers a never-before-seen view of London life and is the most significant change to the Tower Bridge Exhibition since it opened in 1982. The glass floor panels weigh over 1,000 pounds each and are so large and heavy that a 20-strong team was needed to install them