Third Government Farm, Heritage farm complex in Castle Hill, Australia

Third Government Farm is a heritage-listed garden at Gilbert Road, near Old Northern Road, in Castle Hill, The Hills Shire, New South Wales. The site was built in 1801 and is owned by The Hills Shire Council. It is also known as Castle Hill Heritage Park and was added to the New South Wales State Heritage Register on 22 December 2000.

The farm was established in 1801 as a government agricultural site and transformed into an institutional facility in 1811. It subsequently served various roles including as a church and school before its eventual preservation as a heritage site.

The site's name recalls Vinegar Hill in County Wexford, Ireland, the scene of a 1798 rising, and the 1804 battle here is called the Second Battle of Vinegar Hill. About 300 mainly Irish convicts took part; fifteen were shot, nine hanged and nine flogged with 200 to 500 lashes each. Fifty were sent in chains to Coal River, later Newcastle.

The site lies at Gilbert Road, off Old Northern Road in Castle Hill, and is managed by The Hills Shire Council as Castle Hill Heritage Park. Paths cross cleared ground where the 1801 farm stood; the long hut measured 30.5 by 6.1 metres. Allow time to walk between the scattered building sites.

The 4 March 1804 uprising, the Second Battle of Vinegar Hill, was the only recorded armed battle between Europeans in Australia besides the Eureka Stockade. About 300 mainly Irish insurgents fought New South Wales Corps soldiers and militia; fifteen were shot, nine hanged, nine flogged with 200 to 500 lashes, and fifty sent in chains to Coal River, later Newcastle.