It was one of the first Norman castles in England, established in 1066. Later, in 1216, it resisted French siege; and held strong against the Napoleonic wars of the 1800s. It was even used in World War II as a base for one of Britain's finest moments: the rescue of Dunkirk.

Dover Castle, famously known as the "Key to England," is one of the most strategically significant fortresses in Western Europe due to its location at the shortest crossing point of the English Channel. For over nine centuries, it has served as the primary defensive bulwark against continental invasion, from the time of the Iron Age through to the Cold War. Its importance is multi-layered: it houses a rare Roman lighthouse (one of the world's oldest surviving buildings), the massive 12th-century Great Tower built by Henry II, and a labyrinth of secret wartime tunnels. These tunnels were the nerve center for Operation Dynamo during World War II, where the 1940 evacuation of Allied troops from Dunkirk was planned and executed. Even in 2026, it remains a symbol of British resilience and a Grade I listed monument that preserves the tactical military evolution of a millennium.