What makes the structure quietly odd is the combination of its obvious ambition and its brief functional life: built to an H-shaped plan, with a central three-storey block, two projecting south wings, and a dedicated stair tower on the north side, it reads as a serious attempt at a substantial residence. Yet by 1655 to 1656, when the Down Survey documented land ownership across Ireland following the Cromwellian wars, it was already recorded as a ruin.

The land on which the house stands had a long institutional history before any walls went up. Dunganstown formed part of the estate of the Hospital of St John of Jerusalem, one of the medieval military-religious orders that held considerable Irish property before Henry VIII's dissolution of the monasteries. In 1597 the lands were granted to Sir John Hoey, and the house was probably built in the early decades of the following century. The design reflects the transitional architecture of that period: Jacobean gables, which blend English and Dutch Renaissance influences, were fashionable among ambitious landowners in early seventeenth-century Ireland. The structure was apparently damaged in the 1640s, likely during the upheaval of the 1641 rebellion and its aftermath. Inside, traces of what is probably original plaster survive at first-floor level alongside a fireplace, and the attic was once reached by a wooden staircase. Curiously, the hood-mouldings over some windows may post-date the main build, suggesting at least partial repair or modification before the building was finally abandoned. Two granite piers to the north may be eighteenth century, and to the south there is a decorated cut-stone structure described as a wishing seat, its origin and purpose not entirely clear.