Hy Brasil, Heritage-listed house in Avalon Beach, Northern Beaches, Australia

Hy Brasil is a heritage house built in 1936 featuring Hawkesbury sandstone construction with large picture windows and exposed internal stained timber rafters and beams throughout its living spaces. The structure incorporates verandahs surrounding the main living area and includes terraced gardens that descend to a sandstone cliff edge.

The site was part of 490 hectares granted to John Joseph Therry on 31 August 1833, later subdivided as the Pittwater Estate villa lots. Arthur Wilson bought the land on 24 June 1935 and commissioned Alexander Stewart Jolly to design a weekend retreat called 'The Gem', built in 1936. The Herman family nominated it for a Permanent Conservation Order in 1980, placed on 31 July 1981.

The name comes from the mythical Irish island of Brasil, also called Hy Brasil, which Irish folk legend held to contain the Garden of Eden. The house was first called 'The Gem' by Arthur Wilson, who commissioned it in 1935 as a weekend retreat; the present name appears in later ownership. The Herman family, owners from 1958, nominated it for a Permanent Conservation Order in 1980.

Pedestrian access is via a narrow winding path up a steep slope through large sandstone boulders; there is no vehicle entry to the house. Local sandstone has been cut into steps, garden seats, retaining walls, pools and a barbecue. Terraced lawns west of the house end at a sandstone cliff above natural bushland.

The three-metre stone slab used as the mantelpiece is a single piece of Hawkesbury sandstone, and the house is planned around the large central stone fireplace it tops. Jolly's organic style here is credited with influencing the Sydney School movement of the mid-1960s.