 Guildford Castle, one of many fortresses originally established by the Normans to help them subdue the country, was rebuilt in stone and developed as a royal palace in the 12th century.Farnham Castle was built during the 12th century as a residence for the Bishop of Winchester, while other stone castles were constructed in the same period at Bletchingley by the de Clares and at Reigate by the Warennes.During King John's struggle with the barons, Magna Carta was issued in June 1215 at Runnymede near Egham.