One of Napa Valley's last large, untouched properties — which already has entitlements in hand to build an exclusive resort — is up for sale at a watershed price.

The 88-acre undeveloped Calistoga Hills Resort property at the northern end of Napa Valley is being offered for $100 million, Christie's International Real Estate announced on Tuesday.

That would put it in the neighborhood of the nation's most expensive residential sale ever — a waterfront Greenwich, Conn., home on 50 acres with developable land that sold for $120 million in April.

The Calistoga Hills Resort price tag "does put a high water mark in the Napa Valley. It would be the largest land resort sale in Napa," said Hillary Marino, the listing agent for Pacific Union, one of three firms marketing the hillside property near the intersection of Foothill Boulevard, Highway 29 and Lincoln Avenue.

"We see this as a trophy asset, or the buyer as a hotel brand," said Zackary Wright, a Christie's agent based in Beverly Hills.

Calistoga voters in 2013 passed a ballot measure that gave developers of the proposed resort — which includes plans for a 110-room luxury hotel, 20 private villa residences, and 13 estate homes — the ability to proceed after years of controversy and negotiations.

Christie's and Pacific Union were brought in last month to help sell the property, joining an effort led until then by Cushman & Wakefield Global Hospitality, which was hired in late 2013, Marino said.

"There's been interest, but the owner of the property wanted to make sure that every category of investor was able to get information and have an opportunity," Marino said.

Christie's and Pacific Union have extensive contacts in the area of wealthy individuals that will complement Cushman & Wakefield's reach in the institutional investor market, Marino said.

The Calistoga City Council and the city's voters have already approved the equivalent of guaranteed use permits, giving the buyer permission to build a resort and homes on the property — an almost invaluable asset in Napa Valley.

"There are few places as restrictive as Napa for development," said Wright. "It would be worth far less" without those entitlements.

In its announcement, Christie's made clear the brand of buyer it presumes will purchase the property, stating: "The investor may also choose to create additional amenities to the resort's offerings by acquiring nearby top wineries and vineyards that may be available for purchase."

A website created to market the property — — offers buyers information in two languages: English and Chinese.

"We all know that Asians are really interested in buying premium vineyard properties ... so they figure into the formula," Wright said. "But there are Europeans and domestic buyers interested as well. This property is attracting interest from all around the world."

The property owner is Jacqui Safra, a billionaire banker who also owns Spring Mountain Vineyard in St. Helena. The project was previously known as Enchanted Resorts, but the name was changed last year to avoid a trademark fight with an Arizona hotel.