It is one of the best preserved Saxon forts and its lofty position on the south coast made it a perfect part of the defence strategy for the Solent for hundreds of years.
Over the years the castle has also been a favourite with historians and re-enactments, which regularly take place within the stone walls.
Here are some of our favourite memories of Portchester Castle.
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13. Portchester Castle memories
The entrance to Portchester Castle from the moat on November 15, 1975. The News PP3899 Photo: The News archive
14. Portchester Castle memories
Depicting First World War soldiers, gunners of the Brockhurst Artillery with their 2.95 inch mountain gun at Portchester Castle in October 1995. The News PP3906 Photo: The News archive
15. Portchester Castle memories
Guarding the May Queen. Taken at Portchester Castle in 1951 we see boys of the Fareham Sea Cadets fell-in and standing at ease as Guard of Honour to the May Queen of that year. Photo: The News archive
16. Portchester Castle memories
The Militia in Portchester Castle about 1800. Photo: The News archive