A ruined square stone keep is all that remains of Bowes Castle. The medieval fortification was constructed in the late 12th century on the site of a former Roman fort. Both were built to guard the strategic Stainmore Pass that runs east-west over the Pennines between present-day County Durham and Cumbria. The castle was used by Henry II to help defend against a Scottish invasion, which came in 1173 but was rapidly defeated. By the early 14th century the castle had already become obsolete and was largely dismantled after the English Civil War.