|UNESCO World Heritage Site|
|Location||Durham, England, United Kingdom|
|Part of||Durham Castle and Cathedral|
|Criteria||Cultural: (ii), (iv), (vi)|
|Inscription||1986 (10th Session)|
|Area||8.79 ha (0.0339 sq mi)|
|Coordinates||54°46′29″N1°34′34″W / 54.77472°N 1.57611°W|
Durham Castle is a Norman castle in the city of Durham, England, which has been occupied since 1837 by University College, Durham after its previous role as the residence of the Bishops of Durham. Designated since 1986 as a cultural World Heritage Site in England, along with Durham Cathedral, the facility is open to the general public to visit, but only through guided tours, since it is in use as a working building and is home to over 100 students. The castle stands on top of a hill above the River Wear on Durham's peninsula, opposite Durham Cathedral (grid reference NZ274423 ).
Construction of the Castle, which follows the usual motte and bailey design favoured by the Normans, began in 1072 under the orders of William the Conqueror, six years after the Norman conquest of England, and soon after the Normans first came to the North. The construction took place under the supervision of Waltheof, Earl of Northumbria, until he rebelled against William and was executed in 1076.  Stone for the new buildings was cut from the cliffs below the walls and moved up using winches. 
The holder of the office of the Bishop of Durham, Bishop Walcher at the time, was appointed by the king to exercise royal authority on his behalf, with the castle being his seat.  According to UNESCO, 
Walcher "purchased the earldom [of Northumbria] and thus became the first of the Prince-Bishops of Durham, a title that was to remain until the 19th century, and was to give Durham a unique status in England. It was under Walcher that many of the Castle’s first buildings were constructed. As was typical of Norman castles, it consisted of a motte (mound) and an inner and outer bailey (fenced or walled area). Whether the motte and inner bailey were built first is unknown. There is also debate about whether or not Durham Castle was originally a stone or a wooden structure. Historic sources mention that its keep (fortified tower) was built of wood, but there is enough archaeological evidence to indicate that even in the late 11th century when it was first built, it had numerous stone buildings.
A UNESCO site describes the role of the Prince-Bishops in the "buffer state between England and Scotland": 
From 1075, the Bishop of Durham became a Prince-Bishop, with the right to raise an army, mint his own coins, and levy taxes. As long as he remained loyal to the king of England, he could govern as a virtually autonomous ruler, reaping the revenue from his territory, but also remaining mindful of his role of protecting England’s northern frontier.
The Bishops of Durham would not be stripped of their temporal powers until the Durham (County Palatine) Act 1836 returned them to the Crown. 
Another UNESCO report more specifically explains the need for a castle at this location: 
"In defensive terms, Durham Castle was of strategic importance both to defend the troublesome border with Scotland and to control local English rebellions, which were common in the years immediately following the Norman Conquest, and led to the so-called Harrying of the North by William the Conqueror in 1069. ... the Castle was constructed 'to keep the bishop and his household safe from the attacks of assailants'. This makes sense – Robert de Comines (or Cumin), the first earl of Northumberland appointed by William the Conqueror, was brutally murdered along with his entourage in 1069".
In May 1080, the castle was attacked and besieged for four days by rebels from Northumbria; Bishop Walcher was killed. In 1177, King Henry II of England seized the castle after a disagreement with the then-bishop, Hugh de Puiset (sometimes known as Pudsey). 
In the 12th century, Bishop Pudsey (Hugh de Puiset) built the Norman archway and the Galilee of the cathedral.  Other major alterations were made by Bishop Thomas Hatfield in the 1300s, including a rebuilding of the keep and enlargement of the keep mount. 
The castle has a large Great Hall, originally called a Dining Hall, created by Bishop Antony Bek in the early 14th century; Bishop Hatfield added a wooden minstrels' gallery. The Hall was modified and enlarged, then reduced, in size by subsequent bishops.   Today, the Hall is 14 metres (46 ft) high and over 30 metres (98 ft) long. 
The Castle remained the bishop's palace for the Bishop of Durham until Auckland Castle was made the bishops' residence in 1832; the current bishop still maintains offices at that castle, roughly ten miles to the south. Subsequently, Durham castle was donated to the University of Durham  by Bishop William Van Mildert and would later become the college.  The college did not occupy the castle until 1837, after the next Bishop, Edward Maltby, had completed renovations of the building. 
The Norman Chapel is the oldest accessible part of the castle built about 1078. Its architecture is Anglian in nature, possibly due to forced Anglian labour being used to build it. In the 15th century, its three windows were all but blocked up because of the expanded keep. It thus fell into disuse until 1841 when it was used as a corridor through which to access the keep. During the Second World War, it was used as a command and observation post for the Royal Air Force when its original use was recognised. (The cathedral was targeted for a Baedeker Blitz or bombing raid by Germany but escaped because fog rolled in and blocked the pilots' view.) 
The chapel was re-consecrated shortly after the war and is still used for weekly services by the college. 
Tunstall's Chapel, named after Cuthbert Tunstall, was built in the 16th century and is used for worship within the college.  It was modified in the 17th century by Bishop Cosin. 
Durham Castle is jointly designated a UNESCO World Heritage Site with Durham Cathedral, a short distance across Palace Green.  
The UNESCO report provides specifics about the Castle's important aspects: 
Within the Castle precinct are later buildings of the Durham Palatinate, reflecting the Prince-Bishops’ civic responsibilities and privileges. These include the Bishop’s Court (now a library), almshouses, and schools. Palace Green, a large open space connecting the various buildings of the site once provided the Prince Bishops with a venue for processions and gatherings befitting their status, and is now still a forum for public events.
Durham, is a cathedral city and civil parish on the River Wear, County Durham, England. It is an administrative centre of the County Durham District, which is a successor to the historic County Palatine of Durham.
University College, informally known as Castle, is a college of Durham University in Durham, England. Centred on Durham Castle on Palace Green, it was founded in 1832 and is the oldest of Durham's colleges. As a constituent college of Durham University, it is listed as a higher education institution under section 216 of the Education Reform Act 1988. Almost all academic activities, such as research and tutoring, occur at a university level.
The Cathedral Church of Christ, Blessed Mary the Virgin and St Cuthbert of Durham, commonly known as Durham Cathedral and home of the Shrine of St Cuthbert, is a cathedral in the city of Durham, County Durham, England. It is the seat of the Bishop of Durham, the fourth-ranked bishop in the Church of England hierarchy.
County Durham, officially simply Durham, is a ceremonial county in North East England. The ceremonial county was created from the historic County Palatine of Durham in 1853.
The term Norman architecture is used to categorise styles of Romanesque architecture developed by the Normans in the various lands under their dominion or influence in the 11th and 12th centuries. In particular the term is traditionally used for English Romanesque architecture. The Normans introduced large numbers of castles and fortifications including Norman keeps, and at the same time monasteries, abbeys, churches and cathedrals, in a style characterised by the usual Romanesque rounded arches and especially massive proportions compared to other regional variations of the style.
William Van Mildert was the last palatine bishop or prince-bishop as Bishop of Durham (1826–1836), and one of the founders of the University of Durham. His name survives in Van Mildert College, founded in 1965 and the Van Mildert Professor of Divinity.
Auckland Castle, which is also known as Auckland Palace and to people that live locally as the Bishop's Castle or Bishop's Palace, is located in the town of Bishop Auckland in County Durham, England. In 1832, this castle replaced Durham Castle as the official residence of the Bishops of Durham. It is now a tourist attraction, but still houses the Bishop's offices; the Castle is a Grade I listed building.
Hugh de Puiset was a medieval Bishop of Durham and Chief Justiciar of England under King Richard I. He was the nephew of King Stephen of England and Henry of Blois, who both assisted Hugh's ecclesiastical career. He held the office of treasurer of York for a number of years, which led him into conflict with Henry Murdac, Archbishop of York. In 1153, Hugh was elected bishop of Durham despite the opposition of Murdac.
Pickering Castle is a motte-and-bailey fortification in Pickering, North Yorkshire, England.
Sherburn Hospital is a medieval hospital located in the hamlet of Sherburn House to the southeast of Durham, England.
The Diocese of Durham is a Church of England diocese, based in Durham, and covering the historic county of Durham. It was created in AD 635 as the Diocese of Lindisfarne. The cathedral is Durham Cathedral and the bishop is the Bishop of Durham who used to live at Auckland Castle, Bishop Auckland, and still has his office there. The diocese's administrative centre, the Diocesan Office, is located at Cuthbert House, Stonebridge just outside Durham City. This was opened in 2015.
Walcher was the bishop of Durham from 1071, a Lotharingian and the first Prince-bishop. He was the first non-Englishman to hold that see and an appointee of William the Conqueror following the Harrying of the North. He was murdered in 1080, which led William to send an army into Northumbria to harry the region again.
Uhtred of Bamburgh ; died c. 1016), was ruler of Bamburgh and from 1006 to 1016 the ealdorman of Northumbria. He was the son of Waltheof I, ruler of Bamburgh (Bebbanburg), whose family the Eadwulfings had ruled the surrounding region for over a century. Uhtred's death by assassination was described in De obsessione Dunelmi and has been interpreted as beginning of a blood feud.
Elvet Bridge is a medieval masonry arch bridge across the River Wear in the city of Durham, in County Durham, England. It links the peninsula in central Durham and the Elvet area of the city, and is a Grade I listed building.
Æthelwine was the last Anglo-Saxon bishop of Durham, the last who was not also a secular ruler, and the only English bishop at the time of the Norman Conquest who did not remain loyal to King William the Conqueror.
Mitford Castle is an English castle dating from the end of the 11th century and located at Mitford, Northumberland. It is a Scheduled Ancient Monument and a Grade I listed building, enlisted on 20 October 1969. The castle is also officially on the Buildings at Risk Register. The Norman motte and bailey castle stands on a small prominence, a somewhat elliptical mound, above the River Wansbeck. The selected building site allowed for the natural hill to be scarped and ditched, producing the motte.
Events from the 1080s in England.
Farnham Castle is a 12th-century castle in Farnham, Surrey, England. It was formerly the residence of the Bishops of Winchester.
The White Tower is a central tower, the old keep, at the Tower of London. It was built by William the Conqueror during the early 1080s, and subsequently extended. The White Tower was the castle's strongest point militarily, provided accommodation for the king and his representatives, and housed a chapel. Henry III ordered the tower whitewashed in 1240. Today the Tower of London is a museum and visitor attraction. The White Tower now houses the Royal Armouries collections.
Crayke Castle is a Grade I listed 15th-century castle in Crayke, North Yorkshire, England. The castle consists of a restored 15th-century four-storey tower house with attached outbuildings to the rear and a separate ruined 15th-century tower, the "New Tower". It is situated on Church Hill in the village of Crayke.
bishop of durham temporal Powers by Palatine Act 1836.