SAN FRANCISCO – The U.S. housing market may be struggling to regain its footing, but the sale of a single-family home in the heart of Silicon Valley for $100 million shows that luxury properties are still in demand.

Russian billionaire Yuri Milner, a big investor in Facebook, the daily-deal website Groupon and “FarmVille” game maker Zynga, bought the lavish 25,500-square-foot mansion in Los Altos Hills, Calif. The sale is believed to be one of the largest in U.S. history for a single-family home.

Donald Trump sold his Palm Beach mansion for $100 million in 2008 to Russian fertilizer billionaire Dmitry Rybolovlev. Trump told The Associated Press at the time that it was the largest estate sale ever in the United States.

Milner, 49, founder of the Internet investment firm Digital Sky Technologies and chairman of Mail.ru Group, has no immediate plans to move into the mansion, spokesman Leonid Solovyev told the AP. Solovyev and another spokesman for the billionaire declined any further comment.

The mansion’s architect, William Hablinski, said it is a French-style chateau set on 18 acres in hills overlooking San Francisco Bay. Hablinski said the cost of the project, which took about six years to complete, was not a big concern during the building process. He would not comment on how much the seller, Fred Chan and his wife, Annie, paid to build it.

“It did have a budget, it just went far beyond,” Hablinski said.

The estate has a ballroom, screening room, wine cellar, gym, spa and pools inside and out.

“It has a beautiful rotunda in the entryway, flanked by stairs up both sides,” Hablinski said. “And a motor court that ensures security and privacy.”

The $100 million price is based on the documented transfer tax of $110,000, which was provided to the AP by the Santa Clara County Assessor’s Office.

The Wall Street Journal reported the sale price Thursday. That followed a report on the deal last week in the technology blog TechCrunch.