In 1058 Bishop Æthelric of Selsey was consecrated Bishop of Selsey.
Around 1076 Bishop Æthelric of Selsey died.
This monument includes a motte castle situated on the summit of a ridge surrounded by a meander of the River Kennet and within the grounds of Marlborough College within a Grade II Registered Garden (2247). The motte survives as a circular mound of up to 85m in diameter and 18m high. Excavations in 1912 found layers of charcoal and antler picks which have long caused speculation as to whether this was a prehistoric earthwork which was re-used as a motte, although a survey in 2001 did not prove the castle to be anything other than medieval in origin. Further excavations in 1936 found the footings for a curtain wall and the buttress for a shell keep on the summit together with 12th to 13th century pottery. Speculation of this having once been part of a much larger castle with baileys was apparently fuelled by the discovery of a V-shaped profile ditch to the north of the motte in 2000 and it has long been believed that much of the bailey extended to the south although the extent of this is not known. In 2005 further excavations indicated the spiral path which winds its way up to the summit was in existence from 1654. Marlborough was part of a royal borough which was visited often by sovereigns, there is no documentary mention of a castle prior to 1138, but it is thought significant that William I imprisoned Bishop Aethelfric of Selsey in Marlborough and that Henry I held an Easter Court there in 1110. Also, several charters were signed in Marlborough which implies the castle did already exist. The first definitive documentary record was in 1139 when it was held by King Stephen from the Empress Matilda. There was further building work during the reign of Henry II which included the 'Great Tower' and continued from 1175 to 1179. King John had the castle repaired and a ring wall built around the motte in 1209-11. Henry III spent £2000 on works between 1227 and 1272 which included work on two chapels, the hall, the keep, two barbicans, a curtain wall, two bridges, gatehouse, and the Queen's apartments. From 1273-1369 it formed part of the Queen's possessions as her 'Dower House'. However, by 1403 it had deteriorated significantly and subsequently remained neglected. Allegedly the black marble font now in Preshute Church came from the castle chapel and was supposedly used to baptise King John and Edward the Black Prince. The winding path, a grotto (listed at Grade II) and a water tower on top of the motte were all landscape garden features from the 17th to 18th centuries. The grotto was originally part of a canal and cascade feature associated with the mound.