It is medieval, carved directly into the masonry, and equipped with a deep socket for a gnomon, the projecting pin or rod whose shadow marks the hour, along with twenty-four hour lines radiating outward from it. That level of subdivision is unusual; many mass dials of the period mark only the canonical hours used to regulate monastic prayer, so twenty-four lines suggests a more precise, perhaps more practical, interest in timekeeping.

The friary itself dates to the fifteenth century and was built for the Franciscans, a mendicant order whose Irish houses tended toward compact, economical layouts. Muckross fits that pattern well; Harold Leask, writing in 1960, described it as a compactly planned friary of moderate size. It sits in rolling parkland about three hundred metres from the eastern shore of Lough Leane, with a graveyard occupying the ground to the east of the church. The ruin is a National Monument in State care and falls within Killarney National Park. In the 1930s the Office of Public Works cleared decades of encroaching vegetation and undertook substantial consolidation work, concreting over the dormitory floors, excavating to reveal the full original height of the cloister arcades, and pointing the exposed wall tops throughout. It was researcher Brian Thomas McElherron who later identified and documented the sundial, recording its location on the cloister window sill and drawing attention to its twenty-four hour lines.

The cloister at Muckross is one of the better-preserved examples in Munster, and the arcade is easy to walk around. The sundial sits on a sill at roughly hand height, so it rewards a slow circuit of the cloister rather than a glance from the centre. It is the kind of detail that becomes visible only once you know to look for it.