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.
Join our new Portsmouth Retro Facebook group to find more fascinating photos and memories from Portsmouth’s past.

13. Fort Nelson re-enactment memories
2006. The World at War held at the Royal Armouries Fort Nelson searchlight operator Kit Bloom (31) from The Garrison in Barnet North London, with a near unique condition WW11 1939 Mk 1 150cm searchlight. Picturre: Malcolm Wells 061691-174 Photo: The News archive