The King's Mill was one of the earliest and most important buildings of its kind in the city. It had already been established by the time the Great Domesday Book was compiled, indicating an early medieval origin, and it was in continued use until 1800 when it was converted into a private residence. During the watching brief three structural elements, each relating to the medieval structure of the King's Mill. These were: brick lined slots running along the sides of the building, substantial timber piles cut into the area between these slots, and further downstream, a cross wall of worked Folkestone Stone.