Fort Nelson

Fort Nelson is a Grade I listed fortification built between 1862 and 1872 as part of a series of defenses along the chalk ridge of Portsdown Hill, designed to protect Portsmouth from landward attacks. Known as Palmerston's Folly, it features brick walls in English bond, with the outer face of the defensive walls made of flint and decorated with horizontal and vertical bands of brickwork, as well as a blind arcade at the upper level. The fort has a polygonal plan with four vertical faces leading to a deep dry ditch, a fire step behind the parapet, and two-storeyed caponiers at three corners to provide raking fire along the ditches.

Inside the outer structure, there is an embankment with open gun emplacements at the top and a pair of Haxo casemates at the south end. Below the central parade ground, brick-arched passageways, ammunition stores, and staircases connect various parts of the fort, while sunken embrasures for mortars are located behind the caponiers. The rear of the fort features barracks surrounding a triangular court, and the south face is a high brick wall that was originally protected by a continuous ditch, now filled in.

The fort has entrances on each side of a central pointed projection, which was once accessed by a drawbridge. The only notable architectural feature is a bold Norman doorway made of stone with recessed orders. Fort Nelson contains many interesting details of fortification design and remains largely unaltered, aside from the addition of new vehicular entrances when it was repurposed as a store. Although the fort was never attacked and fell into neglect, it is currently being restored as a museum. It is also designated as an ancient monument.