The KPF-designed 72-storey Pinnacle skyscraper will have the highest viewing platform in London, UK, when it opens in 2013.
The 288m spiralling tower has been redesigned and now features a triple-level restaurant at 263m, a five-floor-high public mezzanine level with relics from the Museum of London and a cascade of open-air terraces starting on the 44th floor.
The project secured funding through developer Arab Investments and an additional £550m ($845.6m) of debt financing is lined up.
Upon completion, the scheme will replace 1 Canada Square, Canary Wharf, as the tallest office building in London.
The spiralling skyscraper is also known as "Helter Skelter".