15. Dover Castle
Dover Castle in Kent stands as one of England’s most enduring and strategically significant fortresses. Originally fortified by William the Conqueror soon after 1066, it occupies the commanding height above the Strait of Dover – England’s closest point to continental Europe.
Construction under Henry II in the late 12th century established its central Great Tower, marking the beginning of the castle’s present-day structure.
The fortress underwent major enhancements over many centuries, reflecting evolving military needs – from resisting medieval sieges, such as in the First Barons’ War (1216-17), to surviving modern threats.
In the 18th and 19th centuries the castle was remodelled for artillery defence; a complex network of underground tunnels was created in the cliff face.
These were later used in the 20th century during Operation Dynamo and as a secret command centre in the Second World War.
Today Dover Castle is managed by English Heritage and attracts visitors to its medieval keep, ramparts, wartime tunnels and panoramic views over the Channel.