Nenagh Castle was built by Theobald Walter (the first of the Butlers of Ormond) around 1200. To this day the cylindrical keep adorns the town and like most keeps it formed part of the perimeter of the fortress. The walls have now almost disappeared, but fragments remain. Built from limestone Nenagh Castle measures fifty-five feet in external diameter at the base and rises to a height of one hundred feet. The Castle features four storeys and thanks to a recent renovation this wonderful landmark now represents the town’s premier tourist attraction. The building and has stone spiral stairs to the top. There are 101 steps in all to the top. Access to the tower is through a passageway within the base of the wall. This has low head room and visitors will need to stoop to avoid hitting the stone above.n All children under the age of 18 must be accompanied by an adult. The Castle is open for visitors from April to October with some limited Winter hours.