Earthwork remains of an Iron Age univallate hillfort and a Medieval motte and bailey which reused the former site. The Medieval motte and bailey is said to have been built in 1129-38 and destroyed in 1156. Field Survey between 1993 and 1994 by RCHME recovered further evidence of earthworks and buried foundations suggesting that the site had been used as a military camp during World War 1 and 2. Scheduled.
The castle is beside a lane on the northern edge of the grounds of Hursley Park, owned by IBM. Not known to be open to the public.
A few miles S. of Winchester, at the N. corner of Hursley Park, half a mile from the modern mansion, are the ruins of another episcopal palace, built also by Bishop Henry de Blois for a country residence in 1138, but from the condition of the times, necessarily in the form of a strong castle, surrounded by a wall and a double moat. Henry II., however, in his determined raid against these innumerable castles, caused it to be dismantled, after which the fabric soon went to decay. The only remains of it at the present clay are portions of rough flint walls, and a part of the keep, with traces of the ditches, and the deep castle well. Bishop Poynet surrendered the manor to Edward VI., and in the seventeenth century, by his marriage with the daughter of Richard Major, the place became the property of Richard Cromwell, the ex-Protector, who lived at Hursley Park manor-house after his retirement. He died in 1712, when his daughters, co-heiresses, sold the manor to the Heathcote family. Then the old house was pulled down, and a new mansion built. In the building was found the seal of the Commonwealth, supposed to be the very one taken away by Oliver Cromwell from the Parliament. The fragment left of the ancient castle belonged to the keep, the most massive and the strongest portion of it, which lay on the N. side of the inner area, surrounded by a double moat. In 1551 the place was taken from Bishop Gardiner and given to Sir Philip Hobby, whose descendants kept it till the middle of the seventeenth century. There are no records of any siege sustained at this castle, nor of any fighting in connection with it. (Castles Of England, Sir James D. Mackenzie, 1896)