Somewhere in the flat farmland of County Kildare, a waterway splits in two, curves apart, and encloses a raised circular island before rejoining itself as a pair of parallel channels. This is not accidental drainage or the remnant of a bog cutting. It is a piece of deliberate, seventeenth-century landscape design, an ornamental canal laid out to impress and to order the grounds of a now-diminished estate at Harristown.

The canal runs roughly north-northwest to south-southeast for a total length of around 650 metres, beginning wide, at approximately 35 metres across, before the curious bifurcation near its northern end. There, the water divides and sweeps outward to east and west, enclosing a circular raised area roughly 60 metres in diameter, the kind of geometric flourish typical of formal designed landscapes of the period. The two branches then continue as parallel canals, each about 20 metres wide and up to 2.5 metres deep, leading towards the remains of a large rectangular formal garden. The whole arrangement was associated with Harristown castle and a later fortified house built in the seventeenth century, both of which once anchored a designed landscape garden of some ambition. An estate map of around 1645 already shows the canal in place, and it appears again on Noble and Keenan's 1752 county map and on Taylor's map of 1783, suggesting it was a recognised and enduring feature of the landscape across more than a century of cartographic record.

Today the picture is considerably less composed. The canal floor is damp and reedy, and the banks have been heavily poached by livestock. Near the northern end, a disused railway line and a modern road cut across the channel, layering later centuries of infrastructure over what was once a carefully controlled view. The geometry survives, but only just, readable more in plan than on the ground.