Narrator: Historic castle, royal palace, family home. Windsor Castle, the longest continually inhabited castle in the world, official residence of Her Majesty the Queen, and destination of a million visitors each year. Guide: Down this hill and it will be on your right-hand side, sir. Narrator: Just 23 miles west of London, the castle sits on its striking hilltop site, a potent symbol of the British monarchy. Built by William the Conqueror in the 11th century, Windsor has since been home to 39 monarchs, each shaped the building to their own tastes and needs, and their legacy can be seen throughout the castle. Perhaps most notable was George IV, who in the 1820s gave Windsor its famous skyline, almost doubling the height of the castle's iconic round tower. And as kings and queens had done before him, George IV created magnificent new rooms, but his remain the most dazzling of all. In 1848, Queen Victoria opened the state apartments to the public. They are Windsor's most impressive rooms. Furnishing the splendid interiors are some of the greatest treasures from the royal collection, assembled by kings and queens over the last 500 years. From Old Master paintings to tapestries, porcelain, furniture, even a royal doll's house and armour. As you can guess from the size of it, this suit belonged to the larger than life Henry VIII. Windsor Castle is home to the Order of the Garter, Britain's oldest Order of Chivalry, and its annual ceremony is held at St. George's Chapel. The Garter's star and the Order's motto can be seen all around the castle. Here in St. George's Hall, the shields and armour of over a thousand Garter Knights decorate the walls and ceilings. In 1992, a devastating fire swept through the building. It took 15 hours and 200 firefighters to bring the blaze under control, but some of Windsor's rooms were reduced to burnt-out shells. Five years later, a multi-million pound and award-winning restoration project returned the castle to its former splendour and even added completely new interiors. Today, Windsor is one of the world's few remaining working royal palaces, and the setting for grand ceremonial and state occasions. A national monument, Windsor Castle tells the story of a thousand years of British royal history like nowhere else, and is enjoyed by visitors from all over the world.