Usk castle is situated on a hill above the northern edge of the town of Usk. It began life as a frontier motte and bailey fortification soon after the Norman conquest. Around 1120AD, the castle and the town were formally established. In 1138AD, the castle was captured for the first time by the Welsh.

The first lord to attempt significant improvements at the site was Richard FitzGilbert de Clare who constructed the great tower keep and gatehouse between 1160-1180AD. In 1184AD, the castle fell once more to the Welsh.

Ownership passed to William Marshal, Earl of Pembroke, in 1189AD. He set about making further improvements to the castle, adding stone walls and curtain walls. The round Garrison Tower was added around 1209AD. The castle was captured again in 1233AD during the rebellion of Richard Marshal and Llywelyn the Great - an event which saw a significant uprising against King Henry III combining the forces of a major English Marcher Lord with a Prince of Wales.

Following the failed rebellion, ownership of the castle fell to Gilbert de Clare who built the North Tower (or "Treasury Tower") around 1289AD - presumably as a strong-house for storing the wealth of the castle. Following his death the castle passed to his siter, Elizabeth de Burgh, who oversaw the addition of the Great Hall and made improvements to the gatehouse.

In 14102AD during the uprising of Owain Glyndŵr, Owain's forces laid siege to the castle. Although the castle held, the town was raised to the ground. Following the defeat of Glyndŵr's forces at the Battle of Pwll Melyn just to the north of Usk, the English dominance over Wales was secured and Usk Castle became less significant as a border fortification. It eventually fell into ruin sometime during the middle of the 16th Century and was eventually purchased in 1680AD for use as a private residence.

Today, the castle remains in private hands and the gatehouse serves as a family home. Private ownership allows for a distinctly different experience compared to visiting one of the carefully manicured and sanitised sites in the care of the various heritage bodies. At the time of writing, the castle is open to the public April-September on Sundays and bank holiday Mondays. The grounds have an enchanting quality that makes Usk Castle a unique and charming site to visit.