Deal Castle is an artillery fort constructed by Henry VIII in Deal, Kent, between 1539 and 1540. It formed part of the King's Device programme to protect against invasion from France and the Holy Roman Empire, and defended the strategically important Downs anchorage off the English coast. Comprising a keep with six inner and outer bastions, the moated stone castle covered 0.85 acres (0.34 ha) and had sixty-six firing positions for artillery. It cost the Crown a total of £27,092 to build the three castles of Deal, Sandown, and Walmer, which lay adjacent to one another along the coast and were connected by earthwork defences. The original invasion threat passed but, during the Second English Civil War of 1648–49, Deal was seized by pro-Royalist insurgents and was only retaken by Parliamentary forces after several months' fighting.
Although it remained armed, Deal was adapted by Sir John Norris and Lord Carrington during the 18th and 19th centuries to form a more suitable private house for the castle's captain, which was by now an honorary position. In 1904, the War Office concluded that the castle no longer had any value either as a defensive site or as a barracks, and it was opened to the public when the captain was not in residence. Early in the Second World War, the captain's quarters were destroyed by German bombing, forcing Deal's captain, William Birdwood, to move to Hampton Court Palace, and the castle became an observation post for an artillery battery placed along the shore line. The castle was not brought back into use as a residence and was restored by the government during the 1950s to form a tourist attraction. In the 21st century, Deal Castle is operated by English Heritage, receiving 25,256 visitors in 2008.