Ard Choille, laid out by prominent industrialist, William Macgregor, during 1893-99, is of National significance:
- as an integral component of the Mount Macedon area, a precinct of hill station gardens of outstanding cultural significance;
- as a fine example of the work of the noted landscape designer and nurseryman, William Sangster, of the firm Taylor and Sangster;
- for the intactness of Sangster's original design including stone paths and edges, water features, land forms, water reticulation system and planting;
- for the manner in which the awkward and steeply sloping site has been used to advantage by the incorporation of 'lochs' and cascades, befitting the Scottish ancestry of its owner;
- for its fine collection of rhododendrons and other plants requiring a cool-temperate climate;
- for its location on the northern slopes of Mount Macedon with fine vistas over Mount Diogenes, unusual amongst other hill stations of the area which are almost exclusively situated on the south facing slopes overlooking Melbourne;
- for its retention of a particularly fine and unusual shadehouse, the only example in Australia known to be constructed entirely of metal, apposite for its bushfire prone location and the metalliferous mining interests of its owner;
- for its links with Victoria's nineteenth century acclimatisation demonstrated by the remnants of an early trout hatchery.
- historically, as the hill station of a figure prominent in the early development of Broken Hill and Australian mining of the 1890s.