The ruin of Dunstanburgh Castle.

Recent evidence suggests that the site of the castle was occupied in prehistoric times: however, the principal remains date from the 14th century. In 1313, Earl Thomas of Lancaster, cousin of Edward II of England began construction of a massive fortress. By the time of his execution in 1322, the castle was substantially complete. John of Gaunt improved the castle in the late 14th century as the Duke of Lancaster.

The castle did not play a significant part in the border warfare against Scotland. In the Wars of the Roses the castle was held for the Lancastrians in 1462 and 1464. The damage done was not made good and the castle fell steadily into decay. A report in 1538 mentioned it as being a "very reuynus howsse and of smalle strength" and another source in 1550 described it as in "wonderfull great decaye". It continued to deteriorate and was robbed of stone for the building of other places in the area.

Ref:- Wikipedia