Not one brick has been laid, not one piece of timber has been erected. But already this home comes with a price tag of $155m (£79m) and has triggered considerable controversy.
The price for the property being planned for central Montana by a US real estate magnate makes it, in theory, the most expensive property in the world - beating the record held by an unsold 103-room mansion in Windlesham, Surrey, with an asking price of $139m.
The Montana property is being built by Tim Blixseth, a one-time singer-songwriter who turned to business after failing to hit the big time. As planned, the 53,000 sq ft stone and wood property will be located on the grounds of the Yellowstone Club, a private ski and residential resort that Mr Blixseth has developed near Bozeman.
"I can't believe the interest," Mr Blixseth told Forbes magazine. "Some of [the world's richest] just have to have the best. Price is not an issue."
But not everyone is enamoured by Mr Blixseth's plan. Local environmentalists have complained that private clubs such as the Yellowstone, where members must have at least $3m in assets and pay a joining fee of $250,000, are damaging Montana's environment and pushing up property prices to the detriment of local people. They also point out that Mr Blixseth has a record of planning and environmental infractions and has been fined millions of dollars by state and federal authorities.
"Twenty years ago that whole area up there used to be a great place for the grizzly, the elk and all of the animals. Now it's all houses and roads," said Joe Gutkoski, president of Montana River Action, an environmental group. "Montana is kind of a magical word in the US and we have very wealthy people and they have the dollars to pay for outlandish activities. Blixseth is there to accommodate them."
Reports show that the Yellowstone Club - which employs 400 people and whose members reportedly include former vice-presidential candidates Dan Quayle and Jack Kemp, tennis player Annika Sorenstam and cyclist Greg LeMond - has been fined on a number of occasions for building and environmental violations. In 2004, it was fined a record $1.8m by the Environmental Protection Agency for pollution related to golf course and ski slope erection.
The Bozeman Daily Chronicle reported that Mr Blixseth admitted no guilt, but paid the fines anyway. Then, in November 2005, the agency issued a $165,000 fine to another private Montana resort owned by Mr Blixseth, Lone Moose Meadows, for allegedly destroying wetlands during ski facility construction.
Michael Garrity of Alliance for the Wild Rockies, said: "These private clubs require tremendous amounts of resources. Blixseth has taken high-quality grizzly bear habitat and turned it into a play area for multi-millionaires."
No one from the club was available for comment yesterday. The house, set on 160 acres, will include a chairlift to take the owner to the club's private ski slopes, an indoor/ outdoor swimming pool and a home cinema.
* $139m - Updown Court, a 58-acre estate in Windlesham, England (2006)
* $135m - Skiing estate in Aspen Colorado (2006)
* $125m - Price tag on Donald Trump's renovated estate in Palm Beach, Florida. Six acres of ocean front luxuryReuse content