Mulberry Harbour

The concrete blocks you'll see jutting out of the water near Sheerness aren't debris - they're what's left of Operation Mulberry, one of the war's most audacious engineering feats. After D-Day, the Allies needed to land supplies across the Channel without capturing a proper port, so they built two artificial harbours from scratch. One didn't survive a storm. This one, off the Kent coast, mostly did.

Walking the shoreline at low tide, you can actually get close to these massive Phoenix caissons - hollow concrete boxes that were towed across the sea and sunk in position. It's extraordinary when you realise what they are. There's something properly moving about standing in front of engineering that helped win a war, even if most people pass right by without noticing.

History enthusiasts will find this genuinely compelling, though it takes some imagination to piece together what you're looking at - there's no visitor centre here, just the structures themselves. Families with older kids who've studied the war will get more from it; younger children might find it a bit abstract. Allow an hour, longer if you're keen on photographing from different angles.

It's free and accessible, best visited at low tide when you can get nearest the blocks. If you're staying at Sheerness Holiday Park or Haven Kent Coast Holiday Park, it's an easy detour and worth the walk for anyone with even passing interest in 1940s history.