Tank Traps

These concrete anti-tank obstacles dot the Hertfordshire landscape like forgotten sentries, a visceral reminder of Britain bracing for invasion during World War Two. They're nothing fancy - just squat pyramidal blocks designed to slow or stop German tanks - but their presence across the countryside tells a story most visitors walking past barely notice.

You'll spot them scattered along old roads and across open fields, often grouped in clusters. Some are weathered smooth, others still show the sharp edges of their concrete casting. It's the sheer quantity that hits you: defence in depth, lines of them stretching out as far as you can see. Walking amongst them, you get a proper sense of how seriously this country took the threat of invasion, how near it actually felt in 1940.

They're free to visit and require no planning - you can stop and examine them for twenty minutes or spend longer photographing and exploring the defensive lines. Walkers benefit most, particularly those on rambles near London who fancy a historical diversion. Families with older kids interested in the war will find them genuinely thought-provoking; younger children might find them simply odd lumps of concrete.

If you're based at The Mimms Caravan Park nearby, these make an easy afternoon's exploration without needing to venture far. Best visited in late autumn or winter when vegetation dies back and the obstacles become more visible across the fields. It's understated, unglamorous history - which somehow makes it all the more powerful.