The proximity to the Nepean River and South Creek qualifies it as a key area for food resources for indigenous groups.

Situated on fertile floodplains and well known for its abundant agriculture, Green Hills (as it was originally called) supported the colony through desperate times.

[5][1][7] Peninsula House and the former observatory sit on a 3.23 hectares (8.0 acres) site located close to Windsor on high ground, which, when the river (Hawkesbury) floods, becomes a secluded, unspoilt island, filled with native plants and fauna and protected from development.

The main roof and verandah are slate, the latter supported on delicate cast iron columns, the centre bay marked with a simple pediment.

There are six-panel doors and windows are six pane double hung sashes with stone sills and were originally shuttered, whilst sandstone is used for the foundations, a string course and flagging to the verandah.

The larger one is also face brick with sandstone quoins, classical pediment over a porch and dentilled cornice to the roof parapet.

Windows are of unusual proportions with stuccoed decorations and timber shutters, while the iron segmental roof is double pitched octagonal in form.

[1] Peninsula House and Tebbutt's Observatory is an important and unique group of early and late Victorian buildings remaining in good condition and having an interesting historical genesis.

[10][1] Peninsula House and Tebbutt's Observatory was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

An important and unique group of early and late Victorian buildings remaining in good condition and having an interesting historical genesis.

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

The buildings, with the surrounding rural landscape, make an outstanding contribution to the north eastern area of Windsor.

[8][1] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

[1] This Wikipedia article was originally based on Peninsula House, Tebbutt's Observatory, entry number 28 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence, accessed on 13 October 2018.