Carolands was built by Francis and Harriett Pullman Carolan in 1916 (she was the daughter of George Pullman, then the wealthiest man in Chicago and the inventor of the luxury Pullman railway cars). The four-and-a-half level, 98-room mansion sits on a little more than five acres in Hillsborough. In later years, it was allowed to fall into neglect, but it was purchased in 1998 and restored to its former glory by Charles and Dr. Ann Johnson. The couple donated it to the Carolands Foundation four years ago, and it is open for group tours on Wednesdays at 2 p.m.—but tickets are granted via a lottery system (names are selected at random from a pool of hopefuls).

The house was built in the early 1990s, but it embodies the spirit of an old-school English Tudor. It sits on more than six acres, complete with waterfalls, zen gardens, a koi pond, and an English rose garden. There's also a tennis court, a racquetball court, and an outdoor pool (there's one inside too). According to old real estate listings (it was sold last year, and the asking price was a little more than $28 million), the house has six bedrooms and 10-and-a-half bathrooms.

This house was built during the Depression by Celia Tobin Clark, who (according to a San Francisco Chronicle report), told architect David Adler to spare no expense on the 12-bedroom, 13-and-a-half-bath estate. Its grand ballroom has hosted world leaders from U.S. Republican presidents to King Hussein. Joel Goodrich says he sold the property last year when it was on the market.

Not much is public about this property—even the street view shows it shrouded by greenery. Although it was recently listed for $8.8M, it's currently off market. It was built in 1915 and has nine bedrooms and nine-and-a-half bathrooms.

There's a term for a 12-bedroom, 14-and-a-half-bath home that's on the market for $42 million: trophy property. There's a lot to impress here, including a large house set in the middle of just over 100 acres of vineyards. There's also a car barn, imported limestone fireplaces, crystal chandeliers, and a pool with a waterfall.

In 2011, KPIX reported that this home sold for $100 million. At the time it was reportedly the highest price ever paid for a single family home in the United States. The news station also reported that it was purchased by Yuri Milner, a Russian billionaire who invested in Facebook, Groupon, and Zynga. It was believed Milner had no immediate plans to move in.

We suspect that this photo was taken pre-expansion or perhaps the trees provide excellent cover. According to city records, a request was made in 2005 to permit a 17,389-square-foot home at this address with two levels and a 1,024-square-foot detached building. Obviously, the papers were stamped, because records show it's now 22,006 square feet.

In 2012, Curbed reported that another behemoth house on Broadway was sold for $20 million to tech titan David Sacks. At the time, it was one of the most expensive homes ever sold in San Francisco—and it was only partially finished.