The original castle built by William I was a wooden motte and bailey construction but the castle was extended during the centuries that followed. Henry I, William's son, replaced the original wooden structure with a stone keep and Henry II, the first of the Plantagenet dynasty, added the Round Tower. He also built the first of the castle's medieval state apartments.
During the medieval era the castle experienced two sieges. Firstly when Prince John attempted to take the throne from his absentee brother, Richard the Lionheart. Later, Windsor was again besieged by the nobles as part of the insurrection which culminated in the signing of the historic Magna Carta at nearby Runnymede.
St. George's Hall was created by Edward III for the use of the knights of the Order of the Garter, which he founded on St. George's Day, 1348. He spent the staggering sum of £30,000 on the Castle - the largest crown building project of the medieval period. Since then, an official gathering of the knights of the Garter takes place at the castle every June. Following a meal, the knights walk in procession headed by the Queen and the Duke of Edinburgh, to a service in St. George's Chapel. The fourteenth-century chapel - the burial place of ten sovereigns and setting for many Royal weddings - was mostly destroyed by a terrible fire in 1992. However, it was thoroughly restored to its former glory using traditional techniques.
Although the palace is a working residence it is open to the public and visitors can walk around the State Apartments - the extensive suites of rooms at the heart of the palace. The Semi State rooms, which which has some splendid interiors is open for part of the year when they are not being used. The Stae rooms are furnished with treasures from the Royal Collection, paintings by Holbein, Lawrence, Peter Paul Rubens and Antony van Dyck, tapestries, porcelain, sculpture and armor. The Castle also boasts several other attractions, including the Drawings Gallery and Queen Mary's dolls' house.