Fort Henry

You'll spot the squat Victorian fortification long before you reach it - a stubby brick structure perched above Swanage bay, looking like someone's idea of a proper defensive position that never quite needed defending. Fort Henry sits on the clifftop with views across the water that justify the short walk from town alone, though the fort itself is the real draw for anyone interested in 19th-century coastal defence.

It's a working military installation, so access can be limited depending on the day. When you can visit, you get to wander the gun emplacements and understand how the Victorians obsessed over keeping the French at bay. The views from the ramparts are genuinely excellent - you can see right along the Dorset coast, and on clear days it's the sort of place where you understand why they bothered building it here.

This works well as a half-hour stop rather than a half-day commitment. History enthusiasts will want longer to study the fortifications and imagine the artillery drills, but families with younger kids might find the novelty wears off quickly once they've climbed the ramparts. Admission is free, which at least removes the sting if your visit turns out shorter than expected.

Swanage Bay View Holiday Park sits just 2.9 miles down the coast, making Fort Henry an easy walk or short drive if you're staying nearby. Combine it with the actual town of Swanage - the pier and seafront have plenty going on - and you've got a solid afternoon sorted.