The southwestern, southeastern, and greater part of the northeastern enclosure walls are co-terminous with Cashel's historic town defences, meaning the dead here were, in a literal sense, buried within the fortifications of the town itself.

The graveyard is associated with the medieval parish church of St. John and sits on a slight rise just off John Street. Its rectangular shape and stone boundary give little away about how much further it once extended. In 2000, an archaeological excavation in Agar's Lane, a narrow passage that was only laid out in 1784, uncovered burials dating to the 13th and 14th centuries. Those remains lay beyond the graveyard's present northern boundary, suggesting that the original burial ground was considerably larger, and that successive alterations to the urban landscape gradually obscured or absorbed its outer edges. The lane itself, cut through what had been sacred ground only a few centuries earlier, had effectively sealed those burials beneath a later streetscape.