2. The William A. Clark Mansion, 960 Fifth Ave: Demolished
“Copper King” William A. Clark sunk $6 million (roughly $150 million today) into his mansion at 960 Fifth Avenue according to the Museum of the City of New York. Dubbed “Clark’s Folly,” the mansion took fourteen years to build and when it was finished, consisted of “121 rooms, 31 baths, four art galleries, a swimming pool, concealed garage, and underground rail line to bring in heating coal.” Clark spent only as much time as it took to construct the mansion living it before he passed away in 1925. The home sold in 1927 for less than $3 million dollars and was promptly demolished, making it one of the most short-lived buildings in New York City. A 12-story luxury condo building designed by Rosario Candela stands in its place.