The stronghouse at Mallow is a three storey structure with semi-polygonal wings projecting from the middle of each side, and hexagonal turrets on the NW and SW corners. It was built either by Sir Thomas Norris, or his daughter and her Jephson husband after the town was burnt in 1598. The Jephsons declared for Parliament during the Confederate War, and after successfully withstanding the attack by Lord Mountgarret in 1642, the castle was eventually captured by Lord Castlehaven in 1645. When the castle was burnt in 1689 by the Jacobites, the Jephsons created a more modest mansion further north out of the old stable block. Proving to be ill equipped for defence and having undergone a century of almost constant warfare, the old castle fell to ruin by the end of the 17c.