Sherborne Old Castle was built by Roger, the Bishop of Salisbury, and Abbot of Sherborne. Robert needed a secure home and a small hill surrounded by a lake was chosen as a suitably defendable site. The layout of the castle is roughly rectangular and has four corner towers. The main entrance to the castle is via the gatehouse in the southwest corner.
Stephen arrested Robert, the Bishop of Salisbury. Robert was powerful and could not be trusted. Stephen took control of Robert's castles including Sherborne.