Bowes Castle stands on the site of the Roman fort of Lavatrae. The Normans recognised the strategic importance of the fort, guarding the eastern approach to the Stainmore Pass over the Pennines, and around 1136, Alan, Count of Brittany, built a castle in the north-west corner of the site. After the death of Alan's son, Earl Conan the Little, ownership of the castle passed to the crown. King Henry II immediately set about strengthening the castle against the threat of Scottish raids, and a large stone keep was built. Most of the work was carried out between 1171 and 1174, including repairs that were made following an attack by the Scots in 1173. By 1325 the castle was already falling into ruin, and the crumbling remains of Henry's keep are all that is left.