Trampolines

Concrete slabs mark the spot where anti-aircraft guns once defended Britain's coast during World War Two. These substantial rectangular platforms near Clacton-on-Sea are all that remain of a wartime gun battery, though locals have dubbed them 'trampolines' for reasons that become obvious when you see them. Kids inevitably want to bounce on the flat surfaces, though parents should know the concrete can be slippery when wet.

History buffs will appreciate the strategic positioning overlooking the Thames Estuary, where German aircraft regularly approached during the Blitz. The gun emplacements offered clear sightlines across the water, and you can still make out the mounting points where the heavy artillery once sat. It's a sobering reminder of when this stretch of Essex coastline was very much on the front line.

Families staying at nearby Valley Farm or Highfield Grange often stumble across these wartime relics during coastal walks. Allow half an hour unless you've got enthusiastic young historians in tow - then budget longer for questions and scrambling about. The site works well as part of a longer exploration of Clacton's military heritage, though don't expect interpretation boards or facilities. Just concrete, history, and decent views across to Kent on a clear day.