Visit the tallest building in the UK and EU, and the 5th tallest building in Europe when you visit The Shard in London. Towering 1016 feet (309m) above the streets of the city, its observation decks on the 69th and 72nd floors are the best places to get a birds-eye view of London’s iconic sites. The site can be extremely busy, so it’s recommended to book skip-the-line tickets for a particular timeslot to avoid the long lines.