What remains of a seventeenth-century formal garden at Harristown in County Kildare is not immediately obvious to the eye. There are no walls, no topiary, no grand axis of gravel walks. Instead, the geometry survives as a series of low earthen banks, shallow ditches, and a faint internal avenue, all slowly softening back into the landscape south of the castle that once commanded the estate. The overall enclosure measures roughly 240 metres east to west and 200 metres north to south, a considerable area that speaks to the ambition of whoever laid it out.

The garden appears on an estate map of around 1645, placing its origins firmly in the early modern period when formal geometric layouts, often Continental in influence, were fashionable among the Anglo-Irish landowning class. It was still prominent enough to be recorded on Noble and Keenan's 1752 map of County Kildare and again on Taylor's map of 1783, suggesting it retained some recognised presence on the landscape well into the later eighteenth century. The internal arrangement is legible even now in earthwork form: an avenue running roughly north-northwest to south-southeast divides the western third of the enclosure from the rest. At its southern end this avenue is flanked by two broad, low banks and forms the western boundary of a smaller rectangular compartment, itself defined by a scarp, a fosse (a shallow drainage or boundary ditch), and a further bank. Running south-southeast from this southern section is an ornamental canal, a water feature that would once have been a deliberate and formal element of the overall design rather than a functional drain.