In 1550 the town and friary were burned by O'Carroll.
There are still a few fragments of the Dominican friary founded in 1269.
Of the old castle, called Nenagh Round, dating from the time of King John, there still exists the circular donjon or keep. There are no remains of the hospital founded in 1200 for Austin canons, nor of the Franciscan friary, founded in the reign of Henry III.
The most notable churches are St Gotthard (14th century, remodelled in 1782) St Mary, attached to the Piarist college (1655-1658), the chapel of St Lawrence (13th century) and the church of the Holy Trinity belonging to the Franciscan friary (1655).
The church of Austin Friars, origin- ally belonging to a friary founded in 1253, became a Dutch church under a grant of Edward VI., and still remains so; its style is principally Decorated, but through various vicissitudes little of the original work is left.