By ANNA USHER

Imagine starting the day with a sauna and a cold plunge, ending it with a film under the stars, and never once needing to leave home.

That is the life on offer at Sirius House, a brand-new Mosman home so complete it feels less like a house than a private resort. And no one has ever lived in it.

It sits high on Sirius Avenue, in the tightly held bush above Sirius Cove, the same harbour fringe where Arthur Streeton and Tom Roberts once camped and painted.

Across three levels it gathers a wellness retreat, a private theatre, an infinity pool and a cinema under the open sky.

The price guide is $28 million. For the buyer who lands it, the reward is a home with quite literally nothing left to want.

Michael Coombs of Atlas has sold luxury Sydney real estate for 25 years, and he is not easily wowed. This one stopped him cold.

“We’ve had locals come in thinking it will be another high-quality house, then walk out declaring it’s the best property they’ve ever seen,” he said.

Vogue Living agreed, featuring the home in April for a level of craftsmanship “rarely seen in residential construction”. An architectural triumph, built to the highest specification with no expense spared. It is a line the marketing world wears out, but here, for once, it is simply true.

You feel it the moment you arrive. Walls of warm Taj Mahal quartzite, travertine and timber catch the afternoon light and glow against the bush outside. The kitchen island is a single sculptural sweep, cut from two substantial blocks of Taj Mahal quartzite, acting as a sculptural centrepiece within the room.

And the detail never stops. A basin carved from a solid block of stone. A glowing wall of glass bricks. Speakers tucked unseen into the walls, so the music drifts with you from room to room.

“Rather than following trends, the design focuses on proportion and a restrained palette that allows natural materials to take precedence,” Sici Design director Maria Papadopoulos said.

Even a mishap became a flourish. When a slab of quartzite cracked in the workshop, it was reborn as a custom mirror, the flaw turned into a thing of beauty.

For all the glamour, this is a home built to be lived in and loved. An entire floor is given to wellness: a gym, a sauna, a steam room, and hot and cold plunge baths waiting at the bottom of the stairs. Five bedrooms each open to their own ensuite, with a lift gliding between all three levels. The main suite is a sanctuary of its own, with a walk-in dressing room, an illuminated jewellery cabinet and a couple’s ensuite made for long, unhurried mornings.

Pour a wine from the temperature-controlled cellar. Sink into the library. Host a crowd from a kitchen with its own butler’s pantry and commercial grade cool room.

Even the garage shows off, turning your car on a turntable to face the street.

And the setting may be the finest part of all. The house opens straight onto Sirius Cove Reserve, 1031 square metres where the bush tumbles to the harbour, cockatoos wheel overhead and a foreshore track wanders off towards Taronga and Bradleys Head. Balmoral, the village and the Mosman Bay ferry are all minutes away. This is Mosman at its most magical, and almost no one gets to wake up to it.

Little wonder whispers from Sydney’s well-heeled have started. “I heard the house was the talk of a recent dinner party in the eastern suburbs,” Coombs said.

And there is romance in the ground beneath it.

For decades a modest 1940s cottage stood here. A Sydney schoolteacher, Kathleen Laurence, bought it in 1957 for £9750, and the bushland next door two years later for just 10 shillings. A devoted University of Sydney graduate, she left both to her old university, on one tender condition: that her sister Angela live out her days in the house.

Angela Laurence, once a secretary to General Douglas MacArthur, did exactly that, staying until she died in 2021 on her 101st birthday. The university had waited 49 years.

When the old cottage finally sold in 2022, it fetched $5 million. The home that rose in its place has never been lived in, and now asks more than five times the price.

A once-in-a-lifetime address, waiting for its very first morning.

Sirius House, 9 Sirius Avenue, Mosman, is for sale through Atlas, with a price guide of $28 million.