In 1300 Giolla Iosa O’Reilly attracted a group of Franciscans to found a friary at Cavan and this was sometimes used as a type of retirement home for the local rulers. The Franciscan Friary, or St Mary’s Abbey, remained under the ownership of the Franciscans for almost three hundred years and spanned down Abbey Street and into what is now Bridge Street Car Park. Then during the the reformation the monks were actually expelled. The Friary was burned several times, in 1429 and 1468 by the English, accidentally in 1452 by a monk using a candle and in 1575 by one of the O’Reilly clan.
All that remains is the Bell Tower and this is most likely the oldest building in Cavan Town. Owen Rua O’Neill who was killed by Oliver Cromwell at Lough Oughter Castle, was buried in the Friary but his grave was not marked. After the Franciscans had left, the church was used as a court and then re-built by the Church Of Ireland and used as a parish church until 1815. The Friary fell into ruin in the early 1820s and the stones were used to build houses on Main Street.