Knaresborough Castle stands high on a cliff overlooking the River Nidd. The first reference to a Royal castle at Knaresborough is in the pipe records of 1129-30. In the 13th century King John made improvements to the castle and was a regular visitor, using the castle as a base while he went hunting in the Forest of Knaresborough. The most extensive period of construction took place during the 14th century, and most of the ruins now visible date from this time. Early in the century King Edward I began a programme of modernisation at the castle, but it was his son, Edward II who carried out the most work. Between 1307-12 he spent a total of £2174 redeveloping the castle, which included the construction of a great tower, known as the King's Tower.

In 1331, Edward III's wife, Queen Phillipa, received the Honour and Castle of Knaresborough as part of her marriage settlement. She was particularly fond of the castle and spent many summers there with her young family. In 1372 the castle came into the ownership of her son, John of Gaunt, 1st Duke of Lancaster, and it has remained a part of the Duchy of Lancaster ever since. John of Gaunt's son, Henry Bolingbroke was forced into exile by king Richard II who confiscated the Lancastrian properties; but Henry returned and deposed the king, imprisoning him for one night at Knaresborough before taking him to his castle at Pontefract where he was murdered.

During the Civil War, Knaresborough was held by the Royalists. In 1644 a six month siege of the castle by Parliamentary forces ended in an honourable surrender. The castle was heavily slighted, but survived total demolition after local townspeople petitioned Parliament to allow them to maintain the King's Tower as a prison. As a result, the partially demolished tower and an Elizabethan courthouse, still remain. The courthouse now houses a museum and the castle grounds have been turned into a park from which you can enjoy spectacular views over the valley below.