Situated along the Thames, the Tower of London, also known as Her Majesty's Royal Palace and Fortress, was built in the Middle Ages. The castle was used by the English and British kings as an armory, a royal palace and a prison. Today the Tower belongs to the British Crown and is managed by the Historic Royal Palaces. The Tower was built as a fortress for William the Conqueror to protect him from the potentially hostile citizens of the city of London. English kings and queens used the tower for a temporary stay. It was a tradition that before the day of his coronation, the monarch would stay in the tower and then ride in a festive procession through the city to Westminster. Today the Tower is an interesting attraction for tourism because it contains exhibits on the building itself and its history. In 1988 the tower was declared a UNESCO World Heritage Site.