The Mansion in "Exposed"
On Oct. 19 I watched a rerun of the 3 part story from Sept. 21 which was on FBI, FBI: Most Wanted, and FBI: International.
(I didn't know when I started watching the FBI episode that it would continue for two more hours)
Anyway, when the FBI raided Mr. Kent's mansion, fictionally located somewhere near NYC, I recognized the actual mansion used for exteriors.
It is the Oheka Castle, in Huntington, Long Island, NY, built between 1914 and 1919.
https://www.oheka.com/history.htm
https://www.google.com/search?q=oheka+mansion&newwindow=1&sxsrf=AOaemvJtM2j5CV--kkvp7iIDnmmwvrVnIg:1634942214293&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj1j6Svit_zAhVriOAKHV6eBoYQ_AUoAnoECAEQBA&biw=1920&bih=969&dpr=1
And if any viewer thought that the mansion in the episode looked very large and grand, they are correct. Oheka, with 109,000 square feet, is usually listed as the second largest mansion in the USA, after Biltmore, in Asheville, North Carolina with 178,926 square feet.
"The mansion was built by Kahn between 1914 and 1919, and is the second largest private home in the United States, comprising 127 rooms and over 109,000 square feet (10,100 m2), as originally configured."
https://en.wikipedia.org/wiki/Oheka_Castle
https://en.wikipedia.org/wiki/List_of_largest_houses_in_the_United_States
109,000 square feet is 2.502 acres.
Oheka was partial inspiration for Jay Gatsby's mansion in The Great Gatsby, and film of the Oheka Estate were used for parts of Xanadu in Citizen Kane.
The only other (and now destroyed) mansion which was said to have been at one time the largest in the USA and thus a possible rival in size to Biltmore and Oheka, was the Shadow Brook mansion at Lennox, Mass.
https://en.wikipedia.org/wiki/Shadow_Brook_Farm_Historic_District
Here is a link: https://www.berkshireeagle.com/archives/the-cottager-shadow-brook-a-cursed-cottage-or-just-unlucky/article_c048d172-30e5-58dc-bbd0-bd5a892d1584.html
To an online article saying that: "The house, which was the largest in the country for a single year — until George W. Vanderbilt opened Biltmore in Ashevill, N.C. in 1895 — was 400 feet long and three stories high."
"To appreciate the size of this house, it may be told that the house is 400-feet front by 100-deep, that in walking around it you walk something over a quarter of a mile, that there is an acre of space on each of the four floors".
https://househistree.com/houses/shadow-brook
That would make Shadow Brook House 130,680 squae feet, or 174,240 square feet if the basement is counted.