Forget the megamansions being built in the Hamptons and south Florida — America’s most opulent homes were built decades ago by titans of industry like Alfred I. du Pont and William Randolph Hearst.
The largest historic homes in America, all built before 1952, are sprawling estates located around the country. Many others have been demolished, and are not included on this list.
Some are now publicly owned, others are still in private hands. Quite a few belong to universities, and one even belongs to a presidential nominee.
16. WHITEHALL, PALM BEACH, FLA: 5574 square metres. Henry Flagler, a co-founder of Standard Oil who built this mansion 1902, died after falling down a flight of marble stairs in the home at age 83.
15. THE BREAKERS, NEWPORT, RI: 5804 square metres. The mansion, completed in 1895, was built as the summer home of Cornelius Vanderbilt II.
14. MAR-A-LAGO, PALM BEACH, FL: 5806 square metres. The estate was built by Marjorie Merriweather Post in 1924. It's currently owned by the Trump Organisation and run as a private club.
13. GREY TOWERS CASTLE, GLENSIDE, PA: 6163 square metres. Built in 1893 by William Welsh Harrison, a co-owner of the Franklin Sugar Refinery, the building is now part of the campus of Arcadia University.
12. HEARST CASTLE, SAN SIMEON, CA: 5634 square metres. This castle, built for newspaper magnate William Randolph Hearst and completed in 1947, has 56 bedrooms and 61 bathrooms.
9. (tie) IDLE HOUR, OAKDALE, NY: 6503 square metres. Originally built by William K. Vanderbilt, the mansion served for decades as the home of Dowling College, which closed in August 2016.
9. (tie) LYNNEWOOD HALL, ELKINS PARK, PA: 6503 square metres. The grounds of this 110-room, Gilded Age estate were used to train military dogs during World War II.
9. (tie) WOODLEA, BRIARCLIFF MANOR, NY: 6503 square metres. Originally built as a private residence, the mansion has been home to Sleepy Hollow Country Club since it was founded in 1911.
8. INDIAN NECK HALL, OAKDALE, NY: 6967 square metres. Built as the country home of Singer Sewing Machine Co. president Frederick Gilbert Bourne, the property was acquired by St. John's University in 2001.
7. FLORHAM, FLORHAM PARK, NJ: 7432 square metres. Built in 1997 for businessman Hamilton McKown Twombly, the mansion is now part of Fairleigh Dickinson University's Florham Campus.
6. MEADOW BROOK HALL, ROCHESTER HILLS, MI: 8175 square metres. Scenes from 'Transformers 3' were filmed at this estate, built by the wife of auto pioneer John Francis Dodge.
5. SHADOW LAWN, WEST LONG BRANCH, NJ: 8361 square metres. Built for Woolworth Co. president Hubert T. Parsons in 1927, the building was purchased by Monmouth University and renamed Woodrow Wilson Hall.
4. WINTERTHUR, WINTERTHUR, DE: 8972 square metres. This 175-room house, once the home of Henry Francis du Pont, is now a museum that houses around 85,000 objects.
3. ARDEN HOUSE, HARRIMAN, NY: 9029 square metres. Once owned by railroad magnate Edward Henry Harriman, the home was purchased in 2011 by a Chinese-backed nonprofit, the Research Center on Natural Conservation.
2. OHEKA CASTLE, HUNTINGTON, NY: 10,126 square metres. Completed in 1915, this Long Island mansion was built as the country home of financier and philanthropist Otto Kahn. Now a hotel and wedding destination.
1. BILTMORE ESTATE, ASHEVILLE, NC: 16,258 square metres. This 3200ha is still owned by one of builder George Washington Vanderbilt II's descendants.
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