Castle , standing on the north bank of the Thames - the historic center of London , one of the oldest buildings in England and one of the main symbols of the United Kingdom , holds a special place in the history of the English nation . As the Duke of Edinburgh , wrote in his book dedicated to the 900th anniversary of the Tower , " in its history, the Tower of London has been a fortress , palace , royal jewelry store , an arsenal , a mint , a prison , an observatory, a zoo , a place that attracts touriststhe informal name of the ceremonial guards of the Tower of London . The official English name is the Yeomen Warders . Their body established by King of England and Wales from the Tudor Henry VII, and is a member of the Royal Life Guards . It recruited with an impeccable record of retired non-commissioned officers of the Armed forces of the UK , have served in the armed forces of at least 22 years