This artillery fort was established by Henry VIII on the Hurst Spit between 1541 and 1544 defending the western entrance to the Solent against France and the Holy Roman Empire. In 1649 it was used to detain Charles I before his execution.

Improvements and repairs were made during the French Revolutionary Wars and the Napoleonic Wars and again between 1861 and 1874 when sixty-one gun positions were built in two long granite-faced batteries alongside the older castle. Re-armed in the Second World War it was finally decommissioned in 1956 and has become a tourist attraction. Of the four lighthouses built there from the 18th century onwards, of which the highest, opened in 1867, remains in use.

Coastal erosion is now badly affecting the site and it is threatened with destruction if funding cannot be found to bolster the defences against the sea.