A spec home under construction in Napa Valley is going on the market for $38 million, according to listing agents Ginger Martin and Gregg Lynn of Sotheby’s International Realty.

While winery estates in the region have listed for more, Ms. Martin believes this is the most expensive home without a winery to hit the Napa market.

The St. Helena, Calif. property is about 20 acres, according to developer Patrick Cahill, who has started construction on a contemporary four-bedroom home measuring 6,500 square feet.

A three-bedroom guesthouse is completed and furnished, and there will also be a 776-square-foot “spa house” which the buyer could use as a gym or another guesthouse.

The property will also have a tennis court, an infinity pool at the main house and a lap pool at the guesthouse.

Mr. Cahill, who said he expects construction to be completed in 2016, has also planted about 14 acres of Cabernet Sauvignon grapes on the property.

Via WSJ - CANDACE TAYLOR