The Tithe Barn is a listed building, built in 1087 by Benedictine Monks. It was made to store tithes, the taxes paid to the monks by residents of the monastic estate.

By 1999, the building had fallen into disrepair, and the Priory Church secured funding to carry out major conservation works. Visitors come to learn about the turbulent history of the Priory Church and to enjoy the Abergavenny Tapestry, which took volunteers almost four years to complete. The tapestry exhibition is enhanced by interactive displays.

The publication “An Anatomy of a Priory Church: The Archaeology, History and Conservation of St Mary's Priory Church, Abergavenny” contains a wealth of information concerning the programmes of archaeology, restoration and conservation work that have been undertaken at the Priory over the past 25 years. These studies confirmed that the barn’s foundations are 12th century and the building was extended in the 14th century, with major alterations made in the 16th Century after the priory’s dissolution. The barn operated as a coaching inn during the 17th century and more recently was used as a theatre, discotheque, and discount carpet warehouse.