Windsor Castle has served as a royal home for more than 900 years and is still the largest inhabited castle in the world, used by the Queen as a private home where she usually spends weekends and as an official royal residence where she performs certain official duties. The castle is also a popular visitor attraction, with many parts of it open to the public, and while its old, rotunda tower houses the Royal Archives and the Royal Picture Collection, the Print Room and Royal Library contain precious drawings, prints, manuscripts, and books from the Royal Collection.