Windsor Castle, UK

Windsor Castle is the oldest and largest occupied castle in the world, continuously inhabited for over 11 centuries. This 13-acre fortress on a chalk hill above the Thames serves as the official residence of the British monarch. Its 1,000-year-old Round Tower and sprawling State Apartments offer visitors a living history unmatched by any other European castle. With 1.5 million annual visitors, it remains one of the UK's top attractions, drawing crowds with its majestic architecture and royal legacy.