East Mersea Tudor Blockhouse

Heavy stone walls rise from the Essex marshland like a stubborn survivor from Henry VIII's coastal defence plans. This Tudor artillery fort, built around 1543, was part of a chain designed to keep French invaders at bay - though thankfully it never had to prove its worth in battle.

What remains today is essentially a circular stone tower with walls thick enough to withstand cannon fire. History buffs will appreciate the authentic Tudor brickwork and the way the structure demonstrates 16th-century military engineering. The views across the Blackwater estuary are lovely, stretching towards Bradwell-on-Sea and the open North Sea beyond.

Families staying at nearby Mersea Island Holiday Park or Coopers Beach Holiday Park will find it makes a decent half-hour stop during a coastal walk. The site isn't managed as a formal attraction - it's more of a historical monument you stumble upon - so don't expect guided tours or information boards. Kids might find it a bit underwhelming unless they're already keen on castles and forts.

Access appears to be free, though details are sketchy on the Historic England website. The blockhouse sits on the eastern tip of Mersea Island, easily combined with a trip to the local oyster bars or a walk along East Mersea beach. Well worth including if you're exploring this corner of Essex, but probably not worth a special journey unless you're a proper Tudor fortification enthusiast.