30 St Mary Axe to flight paths for both London City and London Heathrow airports; the revised plan for a lower tower was accepted. The tower's topmost panoramic dome, known as the "lens", recalls the iconic glass dome that covered part of the ground floor of the Baltic Exchange and much of which is now displayed at the National Maritime Museum. "The Gherkin" nickname was applied to the current building at least as long ago as 1999, referring to that plan's highly unorthodox layout and appearance. On 23 August 2000, Deputy Prime Minister John Prescott granted planning permission to construct a building much larger
30 St Mary Axe than the old Exchange on the site. The site was special because it needed development, it was not on any of the "sight lines" (planning guidance requires that new buildings do not obstruct or detract from the view of St Paul's dome when viewed from a number of locations around London), and it had housed the Baltic Exchange. The plan for the site was to reconstruct the Baltic Exchange. GMW Architects proposed a new rectangular building surrounding a restored exchange: it would have the type of large floor plan that banks liked. Eventually, the planners realised that the exchange was