At the time, Government House was in Parramatta and one of Macquarie's first intentions was to travel into the nearby country to discover the best land from which the colony could be provided with food.

It was already known that the most productive area for that purpose was the Hawkesbury River country, but these districts had proven precarious because of severe flooding which caused great losses in crops and stock.

The district became a great supplier of wheat, corn and barley, carried to Sydney by wagons pulled by teams of bullocks or horses.

In 1836 Rose built the huge stone windmill, one of the largest of its kind which gave great service for many years grinding wheat of the surrounding areas.

[3] The windmill is still standing; that is the four storey tower which has long been converted to a water tank; but the top hammer and sails have long-since disappeared.

These and others such as Fairview, Blossom Lodge, Mount Carlon and the big poultry farm conducted by Ingham enterprises are all on the western side of the Appin Road.

A number of the small grants were brought together by purchase and the well-known property of Windmill Hill came into being, owned by William Larkin.

A notice appears in the Sydney Gazette of January 1822 requesting Moses and Michael Brennan of Appin to supply wheat for the NSW Government stores.

The mill that gave Windmill Hill its name was erected in 1846 by Edward Larkin, a Sussex miller who came to Australia with his wife Jane in 1837.

The mill's life was ended as a result of the rust virus that had begun to attack the colony's wheat crop east of the dividing range by the 1850s.

By the 1870s, the rust virus had all but destroyed wheat production in areas east of the dividing range, where climatic conditions helped the disease to flourish.

[1] The timber slab building remains in fair condition and recent works have been undertaken to "mothball" the structure (including new roof gutters and downpipes).

[1] In 1977 the Middle Farm was described as having rendered stone walls and french doors opening to a wooden verandah in the front.

The wooden doorways were described as carefully detailed and the house still had its cedar joinery, with mantelpiece and built-in cupboards each side of the fireplace in the living room.

[9][1] In 1977 a description of the Windmill Hill area describes a ruin of an early house with stone walled rooms at each end of a collapsed timber central part, to the south of Middle Farm.

[9] The area immediately to the north of the dairy at South Farm is heavily overgrown and there are a number of introduced shrubs and small trees adjacent to the large brick cistern.

Other early elements at the site include a well of masonry construction, remains of a timber post-and-rail fence and remnant orchard plantings to the south-east.

When viewed from below the western ridgeline, the few visible elements in the landscape create a strong sense of place and retain the historic setting of the group of farm buildings and their relationship to one another which is increasingly rare as the Cumberland Plain is subjected to development pressure.

The Windmill Hill group has State historical significance as it demonstrates the pattern of middle level farming and settlement in the Cumberland Plain from the 1820s to the early twentieth century.

[1] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

When viewed from below the western ridgeline, there are few visible modern elements in the landscape, providing a strong sense of place and retaining the historic setting of the group of farm buildings and their relationship to one another.

[1] The rural vernacular character of the buildings contributes to the high aesthetic quality of the group, as does the setting with its combination of cleared paddocks and remnant native bushland.

[1] The collection of building ruins and landscape features also has a high level of technical significance as they demonstrate varying construction techniques and vernacular styles from the early to late nineteenth century.

[1] The stone dam, which appears to date from the early to mid nineteenth century, has technical significance, despite its partially collapsed state, as a relatively uncommon example of a substation domestic water supply from this period.

This includes evidence of agricultural practices such as cropping, milling and water management as well as domestic life for the middle class settlers of the area.

The construction of the granary (sandstone) at North Farm has particular significance under this criterion for its ability to inform of the importance of storing and securing grain in the early nineteenth century.

[1] The research potential of the group is increased by the number of possible sites available for investigation within a small geographic area[1] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

Many of the other surviving early colonial homesteads are larger properties by notable architects or with connections to the landed gentry and are single farm sites.

[1] The Pinups radiate at Middle Farm, which appears to be up to 130 years old, is a rare surviving, early example of its kind in NSW.

[1] The ruin of the granary building at North Farm is unusual in that it appears to have a loophole or gun slit in the remaining section of the western wall.