The Shard is the tallest building in London (309m), right next to the London Bridge train station. The Italian architect Renzo Piano designed the Shard, and it was completed in 2012.
The Shard has a hotel and numerous restaurants (31st-33rd floors), and bars (31st and 52nd floor), with beautiful views of the city.
There is also a viewing platform at 244m above ground, which give a spectacular view of London, and with good weather, you might even see 50km away. Visiting the viewing platform requires a ticket, which you can buy outside the building next to the London Bridge Station.