Neptune's Tower
Overlooking Kingsgate Bay east of the tired town of Margate, Kent is a small little fort in a state of decay. Built to resemble a Henrican fortification with a courtyard and bastions, it is in fact, a centuries old folly. Built in the late 1700s by Lord Holland, he of Kingsgate Castle fame, built several follies on his estate because he could I suppose.
Sadly, the tower was pulled down in the 70s and the ruin now stands testament to his wealth. During WWII the folly was a lookout post for the Royal Observer Corps. Now surrounded by a golf course, you can venture in but watch out for the dog poo though.
For a lovely walk, park on the outskirts of Margate and follow the purpose built Princes Walk clifftop path overlooking the bays and sandy beaches. There is plenty of access to the shoreline and at low tide, the chalk stacks at Botany Bay are fun to walk in between. Don't forget your camera.