The ruins of the 15th century Franciscan friary, known as the Old Abbey of Donegal, are located in Donegal town where the River Eske flows into the wide but shallow estuary of Donegal Bay. Just a short distance away is the O’Donnell castle which was also built in the 15th century and was the home of the illustrious O’Donnell chieftains for over 150 years. Up to the mid-1600s many historical and political events centred on the Abbey and the Abbey itself is inextricably linked with that of the history of the O’Donnells and indeed the history of Tír Chonaill. .
The Abbey was founded in 1474 at the request of Nuala O’Connor, wife of Niall Garbh O’Donnell, chief of Tír Chonaill, and mother of Aodh Ruadh O’Donnell. Tír Chonaill was the original name for much of what is now known as County Donegal but it also included parts of Counties Derry, Tyrone, Fermanagh, Leitrim and Sligo. The O’Donnell chieftains had ruled Tír Chonaill for over two hundred years. Nuala sought permission to have an Abbey established in Donegal and made the request to the Franciscan Provincial Chapter meeting being held at Ross Friary, near Headford, Co. Galway in that year. 
The Franciscan Order, in every country, is divided into provinces and in each province, there are a cluster of monasteries. Because of its size, there was only one province in Ireland. The life of the province was regulated by the triennial chapters which were held regularly and addressed matters of discipline, orthodoxy and disobedience and also conducted the necessary negotiations with the bishops and other civic and religious bodies.
The chapter in Ross Friary that year, was reluctant to grant their permission due to commitments they had already made. However, it is said that Nuala pleaded with them:
“What! I have journeyed a hundred miles to attain the object that has long been dearest to my heart, and will you now venture to deny my prayer?
If you do, beware of God’s wrath, for I will appeal to His throne and charge you with the loss of all the souls which your reluctance may cause to perish in the territory of Tirconnell!”. 
Her persistence was rewarded and the chapter even tually gave permission for the friary to be built.
What is surprising is that Donegal already had a Franciscan Tertiary (Third Order) friary in Magherabeg,  about three miles distant from the proposed abbey, which administered its duties in the district between St. Ernan’s and Barnes.  However, as this housed the Third Order Regular it would have been made up of lay men and women who had adapted the three vows of simplicity, chastity and obedience and although they would have administered to the people of the locality they were not necessarily consecrated as religious brothers or ordained as priests.
The new Abbey was built for the First Order, which was the Observant Franciscan Friars, or the Order of Friars Minor. This was a mendicant order (from the Latin mendicare ‘to beg’) which adhered to a lifestyle of poverty, travelling, and living in areas for purposes of preaching, evangelisation, and ministry, especially to the poor. They were also a teaching order which may account for the building of the second abbey as the Irish nobility were keen to have their children given a higher education to ensure their legitimate place in the intellectual world.  The presence of a Franciscan friary would also help to extend the power and influence of the O’Donnell clan. Their influence may also have resulted in the long period of relative peace that ensued in Tír Chonaill after their arrival.
The Gaelic Irish and Old English families in Ireland at that time became generous patrons to the mendicant or travelling orders as they brought great prestige to the areas they settled in and the families came to regard the friaries as places of education, retreat, retirement and ultimately a final place of rest. By 1200 it is estimated that there were 200 religious houses for men and 40 nunneries in Ireland. 
‘For many a valiant chieftain, tired of life’s transient glories and many a noble of the oldest lineage famed in bardic song or chronicled in history, severing every tie that bound him to the world, came to Donegal, and there cast away sword, scutcheon and such worldly vanities, for the poor habit and holy conversation’.