Heritage Open Day: Step inside the restored remains of an Augustinian Priory. Founded in 1136, the history of this Grade I listed former Augustinian Priory is told throughout 5 acres of grounds. Marvel at the magnificent medieval timber roof and late 15th to early 16th century brickwork. By the end of the 15th century, Llanthony was the richest Augustinian house in England entertaining the court of Henry VII in 1500 and 1501. In the medieval period the scholars of Llanthony Secunda created a very special library that is still considered one of the richest and best-documented medieval English book collections in the country. This remarkable library is no longer in Gloucester but is scattered across the world.