Windsor Castle is the oldest and largest occupied castle in the world.

Over a period of nearly 1,000 years it has been inhabited continuously, and altered and refurbished by successive monarchs. Some were great builders, strengthening the Castle against uprising and rebellion; others, living in more peaceful times, created a palatial Royal residence.

William the Conqueror chose the site, high above the river Thames and on the edge of a Saxon hunting ground. It was a day's march from the Tower of London and intended to guard the western approaches to the capital.

The outer walls of today's structure are in the same position as those of the original castle built by William the Conqueror in the 1070s. So too is the central mound supporting the Round Tower and the Upper Ward, where successive monarchs have had their private apartments since the fourteenth century.

In the 1170s Henry II rebuilt - in stone instead of wood - the Round Tower, the outer walls of the Upper and most of the Lower Ward, and the Royal apartments in the Upper Ward.

In the 1360s Edward III, who was born at Windsor, extended the Castle. He created the immense St. George's Hall for the use of the Knights of his newly founded Order of the Garter.

St George's Chapel was begun by Edward IV (r. 1461-70 and 1471-83) and completed by Henry VIII. It is dedicated to the patron saint of the Order of the Garter, Britain's highest order of chivalry, and ranks among the finest examples of late medieval architecture in Western Europe.

Ten British monarchs lie buried in the chapel: Edward IV, Henry VI, Henry VIII, Charles I, George III, George IV, William IV, Edward VII, George V and George VI.

Oliver Cromwell captured Windsor Castle after the Battle of Edgehill in 1642, and for the rest of the Civil War it became a prison as well as the headquarters of the parliamentary forces.

In 1648 Charles I was held there before his trial and execution in London; his body was brought back for burial in St. George's Chapel during a snowstorm.

Following the Restoration, Charles II was determined to make the Castle as splendid as possible. He created a new set of State Apartments in the 1670s, using the skills of the architect Hugh May, the artist Antonio Verrio for murals and ceiling paintings, and the famous wood-carver Grinling Gibbons.

The King's Dining Room and the Queen's Presence and Audience Chambers retain many of these original features. Charles II also laid out the 5km Long Walk leading due south from the Castle into Windsor Great Park.
 
George IV was a great lover of art and fine decoration. Much of Windsor Castle's present appearance is due to the alterations he instigated in the 1820s with his architect, Sir Jeffry Wyatville. The buildings were refashioned in the Gothic style, with the addition of crenellations, turrets and towers.

In the Upper Ward the private apartments were moved from the north side of the quadrangle to the south and east side. The rooms on the north side were designated, as now, as for use on formal occasions and State visits.

One of George IV's most remarkable additions was the Waterloo Chamber, which was created in the 1820s to show portraits commissioned from Sir Thomas Lawrence to commemorate the defeat of Napoleon at the battle of Waterloo in 1815.

They represent the monarchs, soldiers and statesmen who were involved in that defeat and its aftermath. They include George III, George IV and the future William IV, the Duke of Wellington, Field Marshal von Blücher, the Emperors of Austria and Russia, the Kings of Prussia and France, and Pope Pius VII.

Queen Victoria and Prince Albert were devoted to Windsor, where they spent much of their time. It was during the reign of Queen Victoria that, in 1845, the State Apartments were first opened to the public.

Prince Albert died of typhoid at Windsor in 1861 and was buried in a spectacular mausoleum that Queen Victoria constructed at Frogmore in the Windsor Home Park.

During the Second World War, Windsor Castle was home to the young Princesses Elizabeth and Margaret Rose while their parents supported the war effort in London and around the country. Today The Queen uses the Castle regularly, spending most of her weekends there.

The twentieth-century history of the Castle is dominated by the major fire that started on 20 November 1992. It began in the Private Chapel, when a spotlight came into contact with a curtain and ignited the material.

It took 15 hours and one-and-a-half million gallons of water to put out the blaze. Nine principal rooms and over 100 other rooms over an area of 9,000 square metres were damaged or destroyed by the fire, approximately one-fifth of the Castle area.
 
The next five years were spent restoring Windsor Castle to its former glory. It resulted in the greatest historic building project to have been undertaken in this country in the twentieth century, reviving many traditional crafts.

The restoration was completed six months ahead of schedule on 20 November 1997 at a cost of £37 million (US $59.2 million), £3 million below budget. Seventy per cent of the necessary revenue was raised from opening Buckingham Palace's State Rooms to visitors in August and September.

The remaining 30 per cent of the cost was met from savings in the annual Grant-in-Aid funding from Parliament for the maintenance and upkeep of the occupied Royal Palaces. The restoration was undertaken at no additional cost to the taxpayer.

To mark the completion, The Queen and The Duke of Edinburgh held a 'thank you' reception in the restored rooms on 14 November 1997 for 1,500 contractors. On 20 November that year they celebrated their Golden Wedding Anniversary with a ball also held at Windsor Castle.