The Great Hall was built by Walkelin de Ferrers, a Norman baron, in about 1180-90. The remains of other parts of this fortified residence lie beneath the grass of the inner bailey. It was surrounded by earthen banks and stone walls which had at least two towers. To the north were gardens and fishponds.
The castle was the residence of the lord of the manor of Oakham. Sometimes the king held the manor himself and visited the castle.
The Great Hall is famed for its collection of Horseshoes.
By the early 16th century many of the buildings were ruinous. However the Great Hall continued in use as a courtroom, the hub of both the manor of Oakham and County of Rutland. Assize courts were held here until 1970. Today, occasional Crown Courts and Coroner's Inquests still take place.