The rectangular enclosure, measuring roughly 108 metres by 76 metres, appears clearly on Ordnance Survey maps from both 1840 and 1922, and a decoy pond, a shallow artificial water feature used to lure and trap wildfowl, is marked just 20 metres to its east. That so few visitors to the castle today know any of this exists is partly down to the ground simply having been built over, and partly to a set of excavation results that have never been published.

The gardens may well be those rapturously described by Cardinal Giovanni Battista Rinuccini, the papal nuncio who arrived in Ireland in 1645 to support the Catholic Confederates during the 1641 rebellion. Writing after experiencing Bunratty in 1646, Rinuccini declared without qualification that it was the most beautiful spot he had ever seen, adding that in Italy there was nothing to compare with the palace and grounds of Lord Thomond, nor with its ponds, its park, and its three thousand head of deer. Coming from a man steeped in the gardens of Renaissance Italy, that was not a casual observation. Between 1964 and 1967, excavations directed by Marcus Ó hEochaidh for the Office of Public Works uncovered evidence that appeared to confirm the presence of these gardens. The work also revealed that they had been laid out over an earlier moat, which was largely left unexcavated. The findings were never formally published, leaving the relationship between the medieval moat below and the formal garden above as an unresolved question.

The site as Rinuccini knew it no longer exists in any visible form. The area is now occupied by part of the Shannon Shamrock Hotel and surrounding residential properties. The OS maps remain the clearest surviving record of how the garden was arranged, a neat geometric outline from which the park with its deer, the ponds, and whatever else Lord Thomond maintained have entirely vanished.