Somewhere in the fields of Ballysaxhills, County Kildare, there is a place on the map where something once rose from the ground, and where now there is nothing to see at all. That particular kind of absence, a monument that vanished within living memory, is in its own way more unsettling than a ruin.

The mound does not appear on the first edition Ordnance Survey six-inch map of 1838, which makes its origins and early history difficult to pin down. By the time of the revised mapping completed between 1939 and 1940, however, it was clearly present and substantial: an oval earthwork roughly 50 metres along its northeast-southwest axis and about 40 metres across, with a smaller circular platform of around 20 metres in diameter sitting on top at its northeastern end. That secondary raised feature is particularly intriguing. Mounds with tiered or compound profiles are often associated with early medieval activity in Ireland, though without excavation it is impossible to say more with confidence. What is known is that by 1955 the mound was already described as damaged, with trees planted around it, possibly as boundary markers or simply as the kind of informal landscaping that tends to colonise earthworks once their original purpose has been forgotten. By 1972, no visible surface trace remained.