In the parish of Coolagh, about nine miles from Cashel and two miles from Killenaule, not very far from the castle and graveyard of St. Johnstown, Mortlestown Castle stands quite near the residence of Mr. Tom Blackmore, which was built early in the present, or late in the last century by James Glenstone Jacob Esq.
According to the Topographical Survey of Ireland (c. 1948) “the castle is sixty feet high. The thickness as appeared at the doorway was five feet six inches. They are built of brown flagstones, lime and sand mortar. The cornerwork, windows, doorway and stairs were constructed of limestone. The floor resting on the stone arch was lighted by a rectangularly pointed window of chiselled limestone on the west wall. There are windows on the north wall,on which wall there is a flue. There are two on the east wall,the lower large top now being broken, one on the south wall rectangularly pointed, constructed of chiselled limestone and having a stone mullion dividing it into two compartments. The east gable has two pinnacles between which was a passage or platform supported by two circular arches of mason work which rest on the floor in the thickness of the west gable. The arch next to the south wall is seven feet six inches high and five feet nine inches broad. The thickness of the wall in the arch is six feet eleven inches. The square pillar which divides the two arches is one foot three inches in breadth. The arch next to the north wall is the same height and breadth as the other. The pillar stones, as also the quoin stones are lime. The west gable is not pinnacled. The top of it is broken off. In the interior surface of the of the west gable above the floor are placed two rows of flagstones, forming two sides of a triangle and meeting above in a point and projecting beyond the bare surface for the purpose of carrying off the drop from the roof”.
The surname of “Mortal”, more properly “Mortel”, though very common is still to be found in the country. Nine persons named Martelle got grants of land in Ireland in Cromwell’s time. Probably the family of Martelle were of English stock and is not unlikely that the castle may have been built before the time of Cromwell, Martell was one of those soldiers who obtained grants in the barony of Slieveardagh, settled in the castle and gave it a new name. It has been related by men who reside in the neighbourhood of Mortlestown Castle, that the remains of an old church were standing some years ago before some short distance from the castle, and that in ploughing up the land several old metal articles, like chains, were found, but they could not tell what became of them as they were given as play things to the children.
– The History & Folklore of Killenaule/Moyglass 1990