Spectacular and with plenty to explore, Dover Castle, towering high above the ramparts of the white cliffs, is a mighty medieval castle that has served as an important strategic center over the centuries. Most of the castle, including the keep, dates to Norman times. It was begun by Henry II in 1181 but incorporates additions from almost every succeeding century. There's a lot to see besides the castle rooms themselves, most notably the recently opened secret wartime tunnels. Dover Castle played a surprisingly dramatic role in World War II, and these well-thought-out interactive galleries tell the complete story. The tunnels themselves, originally built during the Napoleonic Wars, were used as a top-secret nerve center in the fight against Hitler.