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.