A field wall on the southern edge of a Kildare townland contains two wide, flat relieving arches, the kind of structural feature normally associated with bridges or doorways. Here, though, they exist simply to span a pair of ancient ditches buried beneath the wall, preserving, almost by accident, the outline of something much larger underneath. What the wall is crossing is the eastern arc of a vast enclosure, estimated at roughly 150 metres across north to south, that once wrapped around an entire complex of buildings at Jigginstown.

The enclosure is defined by a flat-bottomed inner fosse, a fosse being a defensive or drainage ditch cut into the ground, running about three metres wide and 1.4 metres deep, with a slight earthen bank beyond it and then a second, narrower outer fosse. Together, these features appear to have enclosed Jigginstown House, its associated garden, a small tower house known as Castle Rag, and a medieval gatehouse. The combination of a substantial residence, a tower house, and a gatehouse within a single enclosure suggests a site of considerable complexity, one where defensive, domestic, and designed landscape functions overlapped rather than sat neatly apart. The ditches themselves probably served as much for drainage and formal landscaping as for any military purpose. Modern development has disturbed some surface elements, though sub-surface remains are thought to be largely intact. When a gas pipe trench was monitored archaeologically in 1996, it revealed that the road running east to west in front of Jigginstown House had been raised significantly in relatively recent times, with stone and clay infill containing modern pottery sitting above the original ground surface, a light yellow clay, at around 1.3 metres below present ground level. That original surface, sealed quietly beneath modern road-making, is part of what remains to be read at this site.