Started by Conan the Little, Earl of Richmond, and finished by Richard the Engineer for Henry II between 1171 - 87, Bowes Castle is sited within the remains of the Roman fort Lavatrae. It's purpose, similar to that of the Roman fort, was to guard the approaches to the Stainmore pass, a highly strategic border area with Scotland.

The entrance to the keep is on the first floor, originally entered through a forebuilding, of which only the footings are visible.

The keep had three levels, the main hall originally sited on the first floor. Bowes was more a garrison post than a residential castle for it was a solitary keep that stood without the protection of curtain walls. A rectangular ditch enclosure was its only outer defence. The ruins of the Roman fort supplied some of the building material and it was raised for a cost of about £600.