Dover Castle, Kent

#summervacay Dover Castle is one of England’s most formidable fortresses and makes for a fascinating #summervacay experience. Known as the “Key to England,” it offers layers of history from the Roman lighthouse to WWII tunnels. In summer, the sprawling grounds are alive with activity—expect reenactments, family-friendly tours, and unbeatable views across the English Channel. Climb the Great Tower, explore the medieval tunnels, or descend into the secret wartime rooms. The warm weather makes walking the outer defenses pleasant, and there’s ample space to relax with a picnic overlooking the sea.