England: Dover Castle
Dover Castle is the largest castle in England. Perched high on the top of the White Cliffs of Dover, it was the primary defensive fortification against the European invasions across the narrowest part of the English Channel between Calais and Dover. The construction began as far back as the 11th century and the castle has been enlarged and fortified further and further over the years. The castle played a major role during the Napoleonic Wars, and both World Wars. It’s a massive site surrounded by walls with the multistory tower complex in the middle. And costs 20 pounds to enter!