Guildford Castle is thought to have been built by William the Conqueror, or one of his barons, shortly after the Norman invasion of England in 1066. Used as a Royal Palace, a prison and a private residence, Guildford Castle and grounds were sold to the Guildford Corporation in 1885. The grounds at Guildford Castle opened as public gardens in 1888 to mark Queen Victoria's Golden Jubilee in 1887. The castle gardens are famous for their vibrant floral displays, centred on the 11th Century Castle Keep.