The Carolands is a 65,000 square foot (6,000 m²) mansion in Hillsborough, California. Enclosing a 75 foot (23 m) atrium, the home holds the record for the largest enclosed space in an American private residence.

Built between 1912 and 1915 at a total cost (including land) of $3,000,000, "The Carolands" has been unoccupied for most of its existence. "The Carolands" was commissioned by Harriet Pullman Carolan , heiress to the Pullman sleeping car fortune. The house originally occupied a 544 acre (2.2 km²) plot of land, situated at the highest geographical point so as to "look down on the Hearsts." Today the house sits on a plot of little more than five acres. Much of present-day Hillsborough, which is the wealthiest suburb of San Francisco, was carved out of the former Carolands estate.

The home, which is more than 80 feet (24 m) in height, is square in shape, with four different chateau-like facades. The home occupies three-fourths of an acre (3,000 m²), and is surrounded on three sides by a "dry moat." Its exteriors were inspired by 17th century designs by Mansart, while its interiors were largely designed by San Francisco architect Willis Polk .

In 1939, the U.S. government considered purchasing "The Carolands" to be the Western White House.

"The Carolands" remains a private single-family residence, and has undergone an extensive restoration since 1998.

See photos of "The Carolands".