Sherborne Old Castle () is the ruin of a 12th-century castle in the grounds of the mansion. The castle was built as the fortified palace of Roger de Caen, Bishop of Salisbury and Chancellor of England, and still belonged to the church in the late 16th century. In the early 1140s, the castle was captured by Robert Earl of Gloucester during the Anarchy, when it was considered, "the master-key of the whole kingdom".King, Edmund. “The Anarchy of King Stephen's Reign.” Transactions of the Royal Historical Society, vol. 34, 1984, pp. 133–153, 134. JSTOR, www.jstor.org/stable/3679129. Accessed 2 May 2020.
