Jewel House. The cannon in front of the building were taken from the French at Waterloo.
You will see a plaque calling this the Jewel House, actually its known as the Waterloo Block and has been used to house the Crown Jewels since 1967. They have been housed in various buildings since 1303 having been brought to the Tower of London after they were stolen from Westminster Abbey. Whichever building the Crown Jewels are kept in it becomes known as Jewel House.
Photography is not allowed inside. The Crown Jewels are housed in bulletproof glass cabinets. They are so valuable that that they are un-insurable. Items on display include The Royal Sceptre containing the world's largest cut diamond, the 530-carat Star of Africa, and the Imperial State Crown which was made for Queen Victoria's coronation in 1938 and is worn by Queen Elizabeth II for the annual State Opening of Parliament, The huge Cullinan I and the well known Koh-i-Noor diamonds. 23,578 in total on display. There are many ceremonial swords, sceptres, Orbs, Crowns and garments on display.
The building can get very crowded as you are first taken around a series of large screens showing details of the collection and examples of when they are worn before reaching the main section.