The main Peel Tower structure of the castle was built in the 13th Century. The tower was on some raised land with a marsh surrounding it and it is also possible that there was a stone structure surrounding this also but not confirmed. There is also suggestion that a moat surrounded it but after exploring this with landscape analysis it does not seem the case.
The main entrance to the tower was though the door in the now first floor Living Room, a ladder would have given access to the structure stopping enemies getting easy access. It is still possible to see the hinge and space for the wooden bolt in the thick walls between the Main Hall and Living Room.