The Franciscan mendicant order played a considerable part in the Irish
ecclesiastical scene during the 13th century. Their rite of poverty and their close contact with the people had its effect on their architecture.
The churches were simple rectangles, divided into a choir for the
brethern and the nave for the laity. The Abbey received a ~generous endowment from the Baron of Upper Ossory in 1302, which
enabled the friars to initiate a building scheme, untypical of the order
in its magnificence. A grand transept, which contained the west aisle and
the chapel of St Mary or the lady's Chapel, was added to the north of the
original Abbey Church. The Lady's Chapel contained three side
chapels in each of which were erected windows with
intersected line tracery or switch tracery, two of which survive intact.