Kilton Castle was a stone castle built on a ridge above Kilton Dale, and that was occupied from at least the twelfth century until the middle of the fourteenth century, when it was inherited by two priests in a row and apparently went out of use. The castle is located above Kilton Dale, south of Skinningrove and west of Liverton Mines. The castle is built on a narrow spur of land that sticks out into the steep-sided valley of Kilton Beck. As a result it was defended by steep slopes on three sides, and only connected to the nearby high ground at one narrow end. The castle was about 300ft long and 60ft wide, although the width varied with the size of the ridge.
The surviving ruins come from two main phases of construction, one in the 12th century and one in the 13th. In the twelfth century phase the curtain wall was build around the entire site, along with a large building at the north-western corner. There must also have been a gate next to this building, but no sign of it remains.
In the thirteenth century a large tower was built about half way along the northern wall of the castle, splitting the interior into two wards. A gatehouse linked the two wards. A small semi-circular bastion was added half way between the hall and the east end of the castle. Finally a large tower was build at the north-east corner of the castle. This was rectangular on three sides, but with a semi-circular northern face. This tower is the best preserved part of the ruin, and the western, northern and eastern walls survive up for two storeys. The two large towers are similar in construction, and were originally faced with well shaped ashlars.
The twelfth century work was probably carried out by the Kilton family, but at some point after 1219 their estates were inherited by the last Kilton's niece Maud. By 1228-9 she was married to Robert de Thweng, her second husband, and the castle remained in the Thweng family until 1374. The last generation of Thwengs had included three sons, but the first died childless and the second and third entered the priesthood. The brother's sister Lucy had married into the Lumley family, so the castle passed into their hands. The castle probably began to fall into ruins after the death of the oldest of the Thweng brothers in 1340-41. It was already described as 'small and worthless' in 1341, but continued to be mentioned from time to time until a final mention in 1696