The Bermingham Tower and its adjoining buildings served as the main cell and dungeon block in the Castle. It was named after Sir William Bermingham who was arrested and imprisoned there, in 1331 by the newly appointed Viceroy, Sir Anthony Lacey. Bermingham was later hanged for treason, 'notwithstanding his great military services against the natives'. Only the base of the medieval tower is unchanged, the upper level was rebuilt in 1777 following an explosion in the nearby armoury. Thinner walls in the upper stories allowed more internal space and ornate decoration was added to the rooms.