It was probably the site of a motte and bailey castle, of which no remains are now visible. A fragment of the motte may have survived until the turn of the century. It was recorded in 1794 that at the west end of Stanhope town, lying between the River Wear, there was a mound called Castle Hill or Castle Heugh. The crown of the hill forms an oblong plateau, and to the north and east, it is defended by a deep ditch. A ditch crosses the crown of the hill and divides it into unequal parts. A wall was discovered, which appeared to defend the whole summit of the hill, built of ashlar, and strongly cemented. It is certain that a castle stood here in the late 13th century as Bishop Bek, granted lands on the west side of the castle. Tradition reports, this was a fortress of great antiquity, and was demolished by the Scots in one of their incursions. It is probable this castle that gave name to the place. Stone-hope, or the fortified hill: or Stand-hope, the hill where the inhabitants made their chief resistance against an enemy. From references, Stanhope castle has been described as a timber structure and then masonry gradually added.
In the 13th century the best hunting grounds for the Durham Bishopric were Weardale forest and Stanhope Park. There was already a gatehouse or castle at Westgate and Wolsingham, and therefore Stanhope Castle was not used and deteriorated rapidly. It was probably a target for pilfering of building materials and firewood. From 1358 it was mainly used for grazing until1462. In this year it was retained in the hands of the Kings Agents, officially unused , but still grazed by the people. The castle site became a copyhold tenement where small structures or buildings were erected and passed through a variety of tenants until 1866.
In Nov 1797 Cuthbert Rippon of London acquired the two parcels of the Castle Heugh and started to rebuild the house with the local architect Ignatius Bonomi of Durham (1787-1870). The house was referred to as Stanhope Castle. The castle then consisted of a four cornered building, two stories high with semi-circular projections at each end and embattled walls. A conservatory was added later leading to a high square tower with large windows. Ignatius was prolific, and was the most important architect to practice in19th century Durham. In 1813 he was appointed County Bridge Surveyor for the Co of Durham. He helped to design numerous bridges, at Frosterley, Shincliffe and the railway bridge at Skerne. His most important buildings include Burn Hall, Egglestone Hall, Lambton Castle, Stanhope Rectory, the female prisoner 'E' wing at Durham prison, and he restored the Norman style windows in Durham Cathedral.
However, due to financial problems the Rippon family advertised the castle as for sale or to let. In 1858 a set of trustees acquired 5 lots of property including the castle. By 1866 only James Heald had survived of the three trustees and in June of that year it was surrendered at an agreed price to the Ecclesiastical Commissioners for England. The surrender was made with the express purpose of extinguishing in 1866 the copyhold, which had first been granted to Thomas Brak in 1358. The castle could now be leased or sold. The Commissioners leased the castle to various tenants, and these tenants acquired the shooting rights to Stanhope Common. In 1875 a new embattled entrance with a balcony was built from the Market Place.
In 1941 the castle was adapted by the Home Office as a School for Boys. The castle remained a school until 1980, where it was made into private apartments. It was made a listed building in 1798 and remains a Grade 2* listed building today. It is now being regenerated to its former glory by Arrandene Ltd in 2012. The grounds to the castle are extensive, including a beautiful lawn to the front of the house, and side elevation, and beautiful woodland pathways lead to the river. Along the banks of the river are Lime trees which lead down to the famous ford, which is now closed, and the famous stepping stones.
Stanhope is a thriving market town, where locals and visitors can find fresh produce displayed in specialist shops, along the high street. There are an assortment of Tea Rooms, including the Royal Tea Rooms that was featured on the main news channel during the Jubilee celebrations', bringing fame to the town. The Dales centre also provides a small cottage industry for local crafts people, and is well worth a visit. Stanhope also has an open air swimming pool of which there are only two in the Northern area. The local public houses are lively, the main nightspot being 'The Bonny Moorhen' which provides a live Band on a Saturday night. It was named after the famous battle at Stanhope between the Bishop's men and the local poachers in 1818, and a ballad is sung to commemorate the stirring tale when the poachers won the day!
The pretty church of St Thomas was built in the 13th century and is a perfect example of a medieval church. The West window has beautiful stained glass dating back from the 14th-16th century. The font dates back to the Anglo Saxon settlers and the Baptismal registers are still intact dating from 1609, Marriage Register from 1613, and Burial register from1595. There are stone coffins and tombs that date back to the time of the crusades. Also in the churchyard is a fossilised tree that dates back millions of years.