aunceston Castle is located at the centre of Cornwall and the original wooden fort was built just after the Norman Conquest in around 1067 by Robert, Count of Mortain. In the 13th century Richard of Cornwall was given permission to build a stone castle on the site. The main bailey is oblong and has two main gates, one on the side towards the town and the other on the opposite side. The main feature of the castle is the large motte with the keep at the top in the north-east corner. At the foot of the motte where the stairs start are the remains of a gatehouse or barbican that would have been used to defend the access to the keep. Around the base of the motte at the foot of the gatehouse is a ditch. A modern bridge now spans the ditch.

The design of the keep on top of the motte is unusual as consists of a shell keep with a round tower inside it. The gap between the outer shell and the tower is quite narrow and is not much more than a passageway. It was not large enough for rooms for example. It appears that the passageway would have been covered as the holes where the wooden floor was inserted can be seen around the outside of the inner keep wall. The walls of the inner keep are very thick and are large enough to contain a staircase that leads up to the upper floors. The floors themselves have gone but a large fireplace can still be seen at the height of the first floor.

The bailey of the castle contained several buildings now gone but some foundations can still be seen. These would have included a chapel and a hall as well as smaller houses for accommodation and workshops. The castle was used during the English Civil War but was not in a good state of repair and was abandoned afterwards.