Dover Castle
Dover, United Kingdom · built 1179
Dover Castle is a medieval castle in Dover, Kent, England and is Grade I listed. It was founded in the 11th century and has been described as the "Key to England" due to its defensive significance throughout history. Some sources say it is the largest castle in England, a title also claimed by Windsor Castle.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).