Fort Nelson was built in the 1860s, as part of a chain of fortifications protecting the great naval harbour of Portsmouth and its Royal Dockyard from a feared French invasion. It now houses the national collection of artillery, held in trust for the nation by the Royal Armouries, with over 350 big guns and historic cannon on display. Visitors can explore 19 acres of ramparts, outer fortifications, secret underground tunnels and ammunition bunkers. This fascinating guidebook is a perfect introduction to a remarkable site.