A fortified site has guarded the River Ness crossing for centuries, although the present Inverness Castle is not the medieval stronghold described in early accounts. Royal castles are documented at Inverness from the Middle Ages, when the town occupied a strategic position between the Scottish crown and powerful Highland lordships. Shakespeare later placed part of Macbeth at Inverness, but the literary castle should not be treated as a description of a surviving building. Repeated rebuilding and destruction left the site with layers of political memory rather than one continuous structure.

During the fifteenth century, control of Inverness reflected struggles between the monarchy and the Lords of the Isles. Tradition associates the castle with attacks during these conflicts, while royal officers used the burgh and stronghold to extend administration into the north. Its best-known sixteenth-century episode came in 1562, when the governor refused entry to Mary, Queen of Scots. Local supporters then took the castle for her, and the governor was executed. The confrontation demonstrated both the symbolic importance of admitting a sovereign and the uncertain reach of royal authority.

The Wars of the Three Kingdoms brought further military change. Cromwellian forces built a large citadel near the river in the 1650s, separate from the older castle site, and later governments again fortified Inverness. After the Jacobites occupied the town in 1746, they destroyed the eighteenth-century Fort George that then stood on the hill before withdrawing toward Culloden. A new Fort George was subsequently constructed on the Moray Firth, while the ruined Inverness position ceased to serve as a major fortress.

The present red sandstone complex belongs to the nineteenth century. William Burn designed the castellated courthouse, completed in the 1830s, and a companion prison was added soon afterward. Their towers, battlements, and commanding hilltop position deliberately evoked a medieval castle while serving modern civil institutions. Courtrooms, offices, cells, and administrative spaces replaced the defensive functions of earlier strongholds. The buildings became a prominent feature of the townscape and a visual shorthand for Inverness even though their architecture was largely historical revival.

For much of the nineteenth and twentieth centuries, the complex remained associated with justice and county government. Changes to court provision eventually opened the way for a new public use, and a major conservation and redevelopment program began in the twenty-first century. The project retains the landmark exterior while adapting interiors and the surrounding grounds. Inverness Castle therefore represents several different histories at once: a strategic royal site, a setting for conflict between crown and region, a romantic nineteenth-century civic building, and a continuing example of how historic landmarks are reworked when their original public functions change.