It was first estimated that restoring the castle would cost PS60 million, and that drying out may take up to ten years. The total cost, however, was closer to PS36.5 million (equivalent to PS68 million as of 2016). The project was completed in 2002. Windsor Castle is one of the largest castles in Europe. Construction on the new castle began in 1099 when William the Conqueror ordered its construction to replace an earlier fortress on the site. The new castle was not intended as a permanent residence for the king but rather as a place where he could shelter from rain and wind. The original wooden structure was replaced over time with stone from local sources. The present day castle is a combination of those original elements and additions made over the next 300 years by various kings and queens. The current castle was built by Edward IV between 1471 and 1483. He wanted a fortress strong enough to protect his wife, Elizabeth Woodville, and their children while he was away at war. During World War II, the castle was used as a hospital and prisoner-of-war camp. After the war, Queen Victoria appointed Sir Charles Barry as the chief architect of Windsor Castle. Under his direction, the castle was restored to its pre-1066 appearance. In 2001, Queen Elizabeth II approved the restoration of her childhood home.