Few of them are likely aware that the ground beneath their feet was once consecrated land, or that the bells ringing across Library Square may be echoing, in some small way, a medieval priory that occupied this exact patch of ground for nearly four centuries.

The Augustinian Priory of All Saints, commonly known as All Hallows, was founded around 1166 by Diarmait Mac Murchada, King of Leinster, the same ruler whose invitation to Anglo-Norman lords would reshape Ireland's political landscape entirely. The Augustinian canons were a religious order who lived communally under the Rule of Saint Augustine, somewhere between monks and parish clergy in their organisation and duties. The priory sat on the eastern side of Hoggen Street, immediately east of the River Stein and close to the shoreline of the Liffey, in what was then the edge of the city. Between 1234 and 1244 it received a grant of lands in the Steynnear, adding to its holdings. Its end came in 1538 with the Dissolution of the Monasteries, but with an unusual twist: the priory's possessions were handed not to a noble or the Crown directly, but to the citizens of Dublin, in formal recognition of their loyalty during the Silken Thomas Rebellion of 1534, when the FitzGerald lord had briefly seized Dublin Castle and threatened the city. That civic ownership did not last long. In the reign of Elizabeth I, the citizens transferred the land to Adam Loftus, Archbishop of Dublin, as the foundation site for a new university. Whatever remained of the priory buildings was not preserved. Its roofing and building materials were carted away by William Brabazon to patch up Dublin Castle.

Trinity College itself now occupies the site, and the priory tower was reportedly incorporated into the north range of the original university buildings near the east end, though nothing of it is visible today. The traditional association between the priory church and the Campanile's location in Library Square gives that spot a quiet historical charge. In 1998, excavations in Library Square uncovered the remains of five skeletons, oriented east-west in the Christian burial tradition, along with a section of medieval wall east of the college Quadrangle, both thought to be connected to the priory. The college is freely accessible during the day, and Library Square is open to the public. The Campanile stands more or less where the priory church once did, and the quadrangle around it covers ground that was, for nearly four hundred years, an Augustinian house on the edge of a medieval city.