One of a series of castles that William I (reigned 1066-1087) established around London, Windsor occupied the nearest strong point in the Thames Valley to the west of the city. By the reign of Henry I (1100-1135) the creation of a large hunting forest, together with the proximity of London, made this a favoured royal residence as well as a fortress. It is the largest inhabited castle in the world and the oldest in continuous occupation. In 1992 a fire damaged approximately one-fifth of the castle; restoration was completed in 1997.