Nenagh Castle is the main monument of the town of the same name in County Tipperary. It is a cylindrical residential tower topped with battlement and a row of tall windows. Currently, it is made available to tourists. There is an observation deck at its top.
The castle was built around 1200 by Theobald Fitzwalter. It is one of only a handful of such buildings in Ireland. In later centuries, the castle belonged to the local bishopric. In 1861, Bishop Michael Flannery decided to add a top floor to the medieval building with a row of narrow windows and a battlement that looks like a crown.
At the beginning of the 21st century, the castle underwent a thorough renovation. It is made available to tourists. You can go up 101 stairs to the top floor and admire the panorama of the town from here. Next to the castle, the remains of the old defensive wall have been preserved.