Dunstanburgh Castle is a 14th-century fortification on the coast of Northumberland in northern England, between the villages of Craster and Embleton. The castle was built by Earl Thomas of Lancaster between 1313 and 1322, taking advantage of the site's natural defences and the existing earthworks of an Iron Age fort. Thomas was a leader of a baronial faction opposed to King Edward II, and probably intended Dunstanburgh to act as a secure refuge, should the political situation in southern England deteriorate. The castle also served as a statement of the earl's wealth and influence, and would have invited comparisons with the neighbouring royal castle of Bamburgh. Thomas probably only visited his new castle once, before being captured at the Battle of Boroughbridge as he attempted to flee royal forces for the safety of Dunstanburgh. Thomas was executed, and the castle became the property of the Crown before passing into the Duchy of Lancaster.
Dunstanburgh's defences were expanded in the 1380s by John of Gaunt, the Duke of Lancaster, in the light of the threat from Scotland and the peasant uprisings of 1381.