It exists as a pattern of anomalies in the earth, a rectangular enclosure measuring roughly 66 metres east to west and 56 metres north to south, with walls so thick, between four and six metres wide, that they may survive only as the splayed bases of what were once substantial masonry structures. Inside, the geophysics detected garden soils and what appears to be a formal layout, complete with a central path and yard surface. The whole thing sits quietly under the grass of Dukesmeadows, a townland whose very name belongs to a later chapter of the story.

The garden takes its identity from a now-vanished building known as the Shirehall, one of the administrative structures attached to Kilkenny Castle's Outer Ward. A shire hall in a medieval castle context was the working courthouse of the sheriff and the venue for the seignorial assizes, the local legal proceedings conducted under the authority of the lord. It was a functional, bureaucratic place, not a ceremonial one. Documentary records from the fifteenth century name the complex consistently as 'le Shirehall gardyne', and a grant dated 22 April 1435, issued by James, Earl of Ormond, to a Kilkenny man named William Boyd, describes land lying outside the garden's gate, bounded by Boyd's own garden on one side and the River Nore on another. Boyd was required to build on the land and return it at the end of a twenty-year term in good repair, the original indenture using the phrase 'styf and stanche'. That same year, custody of what the document calls 'the castle called le Shirhall gardeyne' was granted to a Walter Glerne, who appears again in a 1449 document as tenant of two messuages adjoining the garden. By the time of the Civil Survey of 1654 to 1656, the structure is likely the 'little Castle wth out outergate' recorded there. The Down Survey maps of the same period mark a castle east of the town wall, south of the Ormonde mills, in a townland then called 'Danceing Meadow and other Small Inclosyers'. The castle and its outer ward were probably levelled during the remodelling undertaken by the first Duke of Ormonde, and by 1750 the townland had acquired its present, ducal name.

The 2010 geophysical survey also identified what is likely the Shirehall castle itself, a rectangular masonry structure measuring 13 metres by 11 metres, positioned about 160 metres east of Kilkenny Castle's main gatehouse, with a rubble spread adjoining it. The garden enclosure lies directly to its east, between the probable line of a barbican gate and the old road leading to the Castle Mills. Nothing of any of this is visible at ground level, which makes the meadow an unusual kind of site: one that is entirely present in the archive and almost entirely absent from the landscape.