Defences & Discovery: Fort Nelson Revealed

Fort Nelson runs its Defences & Discovery: Fort Nelson Revealed guided tour on selected Wednesdays throughout the year, with three slots to choose from: 11am, 1pm and 2.30pm. It's a 50-minute walk that takes you through the fort's history, starting from its origins in the 1870s and following it through to its roles in the First and Second World Wars. The fort itself is a restored Victorian fortress on Portsdown Hill, overlooking Portsmouth Harbour, with more than 17 acres of tunnels, ramparts and artillery. It was built to defend Britain's shores and is now a scheduled ancient monument.

Inside, the collection brings together artillery from across the world. You'll see a 15th-century Turkish bombard cannon, a 200-tonne railway howitzer and the infamous 'Big Babylon' Iraqi supergun. The tour is recommended for ages 12 and over, and under-16s need to be accompanied by an adult. It's worth knowing the route isn't accessible: there are changes in surface, low light, spiral staircases, steps and a tunnel, so keep that in mind if you're planning a visit.

Beyond the tour, there are free family activities, an onsite café and exhibitions that change regularly, so it's easy to make a full day of it. The tour costs £12, and the fort is at Portsdown Hill Road, Portchester, PO17 6AN.