Fort Nelson is one of the Palmerston Forts built on top of Portsdown Hill to protect Portsmouth and its Dockyard. It was built in the 1860s after the Royal Commission report of 1859. It lies between Fort Wallington (now partially demolished) and Fort Southwick.
The fort had a brief operational history was only fully armed in the 1990s and disarmed by 1907. In World War II the fort was used as an anti-aircraft ammunition store and a number of magazines were built on the former parade ground. Disused from the 1950s, the fort was eventually sold to Hampshire County Council in 1979. After restoration, it opened to the public in 1994 and became part of the Royal Armouries a year later. It now - appropriately - houses their collection of artillery and is open all year round. The tunnels beneath the fort that connect magazines and gun emplacements can also be explored.
Fort Nelson is Grade I Listed.