The Castle can be visited
Barnard Castle

In the town of Barnard Castle in County Durham, England, is the medieval castle ruin Barnard Castle. Its history dates back to the 11th century.
History+
The origins of Barnard Castle lie between 1095 and 1125, when Guy de Balliol began its construction. His nephew Bernard de Balliol and his son Bernard II continued to expand the building between 1125 and 1185. In 1216, the castle endured a siege by Alexander II, King of Scotland. Later, in 1296, the castle passed into the possession of the Bishop of Durham. In the 15th century, it came into the Neville family through marriage.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 54.5434, -1.9265