The London Eye is a giant Ferris wheel located on the edge of the River Thames. It is 135 metres tall and has a diameter of 120 metres. A short walk away, the area is home to the London Aquarium, Elizabeth Tower, the Houses of Parliament, Westminster Abbey and Nelson's Column. In 2013, the tallest building in London, The Shard, opened a viewing platform to the public. Other major tourist attractions in London include the Tower of London, Buckingham Palace (although this is only open to the public during a limited number of months in the summer), Tower Bridge Experience, Madame Tussauds, ZSL London Zoo, London Dungeon and St Paul's Cathedral.