Jaywick Martello Tower (C)

You'll spot this squat, circular brick tower rising from the Essex coastline just east of Clacton-on-Sea, a relic from the Napoleonic Wars that's been standing guard over this stretch of beach for over two centuries. Built around 1812, it's one of a chain of defensive towers constructed when invasion fears were running high, and it's surprisingly solid for something that never actually fired a shot in anger.

It's a modest stop rather than a destination in itself - you can walk around the outside and get a decent sense of the architecture and its historical purpose in about 20 minutes. The tower sits right on the seafront, so on a decent day the walk there from Clacton is pleasant enough, though the surrounding area is fairly unremarkable. History types will appreciate the period detail, but families after a proper afternoon outing might find themselves wanting more.

Accessibility seems limited from what you can gather - there's no visitor centre, no entry fee listed, and visits appear to be external viewing only. Best approached as a quick detour if you're already in the area rather than a deliberate expedition. It works well if you're staying at one of the nearby caravan parks like Seawick or St Osyth Beach, which are within easy walking distance. Combine it with a stroll along the seafront and a chip supper in Clacton for a proper seaside afternoon. Go when the weather's cooperating, obviously - wind and rain don't improve a brick tower.