It was one of five defensive forts built on the summit of Portsdown Hill during the 1860s, overlooking the city. In times of war a garrison of about 200 volunteers, as well as regular army officers, would have helped to guard the fort.
Nowadays the fort is open all year round as a museum where visitors can learn more about the artillery stored there and Fort Nelson’s secret underground tunnels.
The site is also popular with re-enactments which regular take place.
Here are a few of those events taking place, featuring in photos from The News’ archive.
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5. Fort Nelson re-enactment memories
2016. A live firing exercise using blank ammunition has taken place at Fort Nelson. Thrilled audiences witnessed a self propelled World War Two gun. Picture Ian Hargreaves 160714-4 Photo: The News archive
6. Fort Nelson re-enactment memories
2010. Fort Nelson on 8th May, the 65th Anniversary of the end of the war in Europe. Geoff Pye (60) from Portsmouth, an interpreter at Fort Nelson taking the part of a Submariner Sub Lt.in WW11 before the visitors were invited to see a film about the Enigma Machine and Submarine U110. Picture: Malcolm Wells 101446-8948 Photo: The News archive
7. Fort Nelson re-enactment memories
2010. Second World War event at Fort Nelson. Martin Standbridge dressed as a Russian forces Sargent mans the command post in the fort. Picture: Will Caddy 101070-17 Photo: The News archive
8. Fort Nelson re-enactment memories
2005. (left to right) William Stuart-Dickey (27) dressed as an Private and as an orderly/stretcher bearer in the RAMC takes some advice from his senior officer (right) Julian Farrance (39) who takes the part of a Lieutenant in the RAMC during The Great War - the re-enactments were part of the weekend demonstrations at Fort Nelson - The Royal Armouries. Picture: Malcolm Wells 052097-89 Photo: The News archive