"One of the remaining original features of the castle"
The top floor of the peel tower is the Attic, this is located at the top of the upper spiral staircase and also gives access to the Ramparts.
The main purpose of the attic would have been for the security staff of the castle to live, they were known as "the Constable". Other members of staff may also have slept here, that being the person in charge of the household who was known as "the Steward", and "the Marshal" who was the person in charge of all communication. These three were very important during the medieval times so would have had better surroundings than the other staff who would have lived in huts outside the castle.
During later years the attic may have been used by female members of the household to sew and weave garments.