The Biggest Mansions In America

If you had unlimited money, what sort of dream house would you build for yourself? For some people, their dreams came true — big time. These stunning American mansions all clock in at more than 20 times the size of the average American home when measured by square footage. Many of them are now wonderful museums, others are college campus halls and some are still private residences. A few aren't even fully constructed yet. Here are 21 of the biggest mansions in America.

#21 Grey Towers Castle (Glenside, Pennsylvania): 53,564 square feet

Grey Towers was constructed in 1893 as the estate of sugar magnate William Welsh Harrison. In 1929, two years after Harrison's death, Arcadia University purchased Grey Towers from the Harrison family for $712,500. The castle is a multi-use building on Arcadia's beautiful college campus. Select freshmen are even allowed to live inside.

#20 White House (Washington, DC): 55,000 square feet

With 132 rooms, including 35 bathrooms, the current White House has been home to every sitting president since James Monroe in 1817. The original famous landmark was destroyed by a fire in 1814. The mansion has been known as the "President's Palace," the "President's House" and the "Executive Mansion." President Theodore Roosevelt gave the mansion its current name in 1901. 

#19 Ralston Hall (Belmont, California): 55,000 square feet

Entrepreneur William Chapman Ralston purchased a two-story California villa from an Italian nobleman in 1864. In four years, Ralston expanded the modest villa to a whopping 55,000 square feet. In 1922, the Sisters of Notre Dame de Namur purchased the estate, and for 90 years, it was used as a classroom hall for Notre Dame de Namur University students and teachers. As of 2012, the mansion has been under repairs.

#18 Carnegie Mansion (New York City, New York): 56,368 square feet

American industrialist Andrew Carnegie forever altered life on Fifth Avenue when he built his 64-room mansion in 1902. Located farther north than any of his friends' homes, Carnegie's mansion was sophisticated in its central heating and cooling technology and modern steel-frame construction. In 1976, the mansion opened as the Smithsonian Institution's Cooper-Hewitt Museum.

#17 Whitehall (Palm Beach, Florida): 60,000 square feet

Whitehall was built in 1902 for railroad tycoon Henry Flagler. Widely regarded as the man responsible for turning Florida into a tourist destination, Flagler died in 1913 after suffering a fall in Whitehall. Today, the 55-room mansion still drips with marble, gilding and murals and is open to visitors. Add a stop at the estate's Flagler Museum to your list of things to do in Florida that aren't Disney or the beach.

#16 The Breakers (Newport, Rhode Island): 62,482 square feet

Built as the summer home of Cornelius Vanderbilt II in 1895, The Breakers is one of America's finest surviving Gilded Age mansions. Built in the Italian Renaissance style on 13 acres overlooking the Atlantic, its well-groomed gardens and interiors rich with imported marble and other high-end architectural elements make it a must-visit museum.

#15 Mar-a-Lago (Palm Beach, Florida): 62,500 square feet

Mar-a-Lago officially opened in 1927 after four years of construction. The hurricane-resistant structure was built for socialite and cereal heiress Marjorie Merriweather Post. When Post died in 1973, she willed the estate to the federal government, which found the property too difficult to maintain. President Donald Trump purchased the property in 1985 and for a decade used it as a private residence before turning it into a private club.

#14 Dumbarton Oaks (Washington, DC): 64,000 square feet

After passing through several hands, the Dumbarton Oaks estate was greatly expanded by Robert and Mildred Bliss throughout the mid-19th century. In 1940, the couple transferred the almost 55,000-square-foot property to Harvard University, Robert's alma mater. Today, the estate houses a museum, library, garden and research institute. 

#13 Florham (Madison, New Jersey): 65,465 square feet

Designed in the 1890s to replicate a wing in Henry VIII's Hampton Court, the Florham Mansion was first the country estate of Florence Vanderbilt and her husband, Hamilton Twombly. The mansion was as lavish as you'd expect from the Vanderbilts: 100 rooms, and gardens designed by the same man who designed New York's Central Park. In 1957, the 178-acre estate was acquired by Fairleigh Dickinson University to serve as a third campus. The mansion is now known as Hennessy Hall.

#12 Stan Hywet Hall (Akron, Ohio): 64,500 square feet

This Tudor Revival-style estate was constructed between 1912 and 1915 for Goodyear Tire co-founder F.A. Seiberling. Inspired by English country homes, the mansion is decorated with 21,455 panes of glass and 23 fireplaces. Today, about 95% of the estate's furnishings are original. Nestled within the estate are four gardens, a grape arbor, an apple orchard and a conservatory. Tours are typically offered April to December but virtual tours are also available.

#11 Xanadu 2.0 (Medina, Washington): 66,000 square feet

Microsoft is one of the world's biggest businesses with humble beginnings, but founder Bill Gates' home is anything but humble. Gates and his wife Melinda live in a home informally dubbed "Xanadu 2.0," after the mansion in the movie "Citizen Kane." The main house contains six kitchens, seven bedrooms, 24 bathrooms and six fireplaces. As can be expected from Gates, the estate is chock-full of high-end tech. Visitors use wearable pins to control the lighting, room temperature and art designs in the guest house.

#10 Fair Field (Sagaponack, New York): 66,395 square feet

Built in 2003 for junk bond billionaire Ira Rennert, Fair Field sits on a 63-acre estate. The main house has 29 bedrooms, 39 bathrooms, three pools, a 164-seat theater and its own power plant. Its construction was so controversial that writer James Brady wrote a novel about it called "The House That Ate the Hamptons."

#9 Hearst Castle (San Simeon, California): 68,500 square feet

Built between 1919 and 1947 for publisher William Randolph Hearst, Hearst Castle was designed by one of America's earliest major female architects, Julia Morgan. The entire complex is made up of the massive Casa Grande, as well as three sprawling guest houses, elaborate gardens and one of the most beautiful swimming pools in the world,  the 345,000-gallon Neptune Pool. Today, the enchanting castle is a California State Historical Monument and is open to visitors.

#8 Lynnewood Hall (Elkins Park, Pennsylvania): 70,000 square feet

Constructed in 1900 for Philadelphia businessman Peter A.B. Widener, Lynnewood Hall has been left vacant for over a decade. Widener's son and grandson died in the Titanic's 1912 sinking, and Widener died three years later. An avid art collector, Widener donated his collection, valued at $10,000,000, to the National Art Gallery in Washington, D.C.

#7 Woodlea (Briarcliff Manor, New York): 70,000 square feet

The 75-room Victorian-style Woodlea mansion was completed in 1893, costing $2.5 million to build at the time. Originally owned by Colonel Elliott Fitch Shepard, a founder of the New York Bar Association, the mansion later became the clubhouse of one of America's top-rated country clubs and golf courses.

#6 Meadow Brook Hall (Rochester Hills, Michigan): 88,000 square feet

Built in the 1920s for Matilda Dodge Wilson, the widow of Dodge motor car company founder John Francis Dodge, Meadow Brook Hall boasts 110 rooms. In 1957, Wilson and her second husband donated the hall, its collections, the estate's 1,500 acres and $2 million to found what would become Oakland University.

#5 Versailles (Windermere, Florida): 90,000 square feet

Famed Florida couple David and Jackie Siegel are over 18 years into constructing what they've dubbed a modern-day Versailles. Their efforts were documented in the 2012 film "The Queen of Versailles." Construction hasn't exactly been a breeze; it stalled in 2009 as the financial downturn hit. In 2019, according to the Orlando Sentinel, Jackie expressed regret in ever having started building the home.

#4 Shadow Lawn (West Long Branch, New Jersey) : 91,469 square feet

Constructed in 1927, Shadow Lawn was built in the location of another mansion that was once inhabited by President Woodrow Wilson and later burned down in a fire. In 1955, the second Shadow Lawn was purchased by Monmouth University and renamed Woodrow Wilson Hall. Beyond just a beautiful mansion, Shadow Lawn is a movie location you can actually visit too. It was used as Daddy Warbucks' mansion in the 1982 film "Annie."

#3 Winterthur (Winterthur, Delaware): 96,000 square feet

Built in 1837, Winterthur underwent massive renovations in the 20th century by Henry Francis du Pont that doubled its size. The additions were largely constructed to hold du Pont's massive collection of American art. Today, its 175 rooms house 90,000 objects dating as far back as the 1600s as well as research and conservation facilities.

#2 Oheka Castle (West Hills, New York): 109,000 square feet

Oheka Castle was built as the country home of investment financier Otto Hermann Kahn between 1914 and 1919. It contains 127 rooms and was once part of a 443-acre estate. After Kahn's death in 1934, the castle passed through several owners before being taken over by the Eastern Military Academy. After the school closed in 1979, the house nearly burned down several times. It has since switched owners again and been fully restored. Today, it's one of the country's most high-end wedding venues.

#1 Biltmore Estate (Asheville, North Carolina): 175,000 square feet

The Biltmore Estate isn't just the largest privately owned house in the United States — it blows the competition out of the water. Built in the style of a French chateaux between 1889 and 1895 for George Washington Vanderbilt II (who dubbed it his "little mountain escape"), the mansion boasts 35 bedrooms, 43 bathrooms, and 65 fireplaces. The surrounding Antler Hill Village is a charming town that looks stuck in time.