Kingswear Castle is an artillery fort, built to protect Dartmouth harbour in Devon, England. It was constructed between 1491 and 1502 in response to the threat of French attack and was one of the first purpose-built artillery forts in Britain. By the end of the 16th century, however, improvements in the range of artillery weapons had reduced the utility of the castle. It took part in the English Civil War and continued to be armed until the early 18th century, but fell into ruin. Restored as a summer house in 1855, in the 21st century it is managed by the Landmark Trust as a holiday let.