The label is curious. A cairn, in this context, is a prehistoric pile of stones typically raised over a burial, and this one measures around sixteen metres in diameter and stands some 1.8 metres high. There is nothing castle-like about it. Yet the name stuck to the map, and the place has carried that slightly bewildering designation ever since.

The local name adds another layer of confusion. People in the area refer to this mound, and to a separate modern cairn on the western shoulder of the same hill, collectively as "Daddy Morey's Castle". Whether "Daddy Morey" is a corruption of "Money's" or an entirely independent piece of folk memory is not clear, but the result is that two quite different structures, one prehistoric and one modern, have become tangled together in both name and identity. The prehistoric cairn has a more recent cairn built into its centre, rising to about 1.2 metres, which further complicates any reading of the original structure. This kind of layering, where later activity disturbs or obscures an older monument, is common enough on prominent hilltops, where the urge to mark a high point apparently persists across centuries.

The two cairns on Mount Hillary are close enough in appearance, and similar enough in their shared nickname, that walkers and locals have long conflated them. Anyone approaching from the west might easily assume they have found the older structure when they have not. The prehistoric cairn is the one on the south-eastern shoulder, higher and broader at the base, with the smaller modern addition visible at its crown.