200 foot Sound Mirror

There's a massive concrete wall standing 200 feet tall on the Romney Marsh, and it looks like something from a Cold War thriller - except it predates that era entirely. This is the Sound Mirror, built in the 1920s as an experimental early warning system. Before radar existed, the British military thought they could detect incoming aircraft by sound alone, bouncing noise off this enormous curved barrier to pinpoint enemy planes.

It doesn't work, obviously. Modern visitors quickly realise why - you'll struggle to hear much of anything except the wind and the occasional sheep. But that's precisely what makes it compelling. The structure itself is genuinely striking, a raw concrete curve dominating the flat landscape near New Romney. You can walk right up to it, touch the pitted surface, and stand where soldiers once listened intently for the rumble of German engines.

This appeals most to history buffs and industrial archaeology enthusiasts rather than families after a day out. Kids might find it mildly interesting for five minutes, then want to move on. Allow 20-30 minutes unless you're properly keen on Cold War-era defence systems.

It's free and accessible year-round, which is brilliant. The site sits perfectly between the holiday parks clustered around New Romney - Parkdean Resorts Romney Sands is barely half a mile away, making it an easy addition to a caravan holiday on the Kent coast. Combine it with a walk across the Marsh itself, which stretches endlessly in every direction. Worth the detour if you're already in the area, but don't make a special trip unless you're genuinely fascinated by Britain's forgotten military experiments.