This mega palace on fifth avenue belong to Andrew Carnegie and his wife Louise. Andrew Carnegie was called the "Steel King" and owned Carnegie Steel. When he retired he sold Carnegie Steel to J. P. Morgan for $400 million and built a beautiful estate in Scotland on 40,000 acres called "Skibo Castle". He also wanted a New York City residence so he could manage his charity ventures. Andrew planned to give away all of the $400 million, except for $10 million for his family, and he needed city headquarters to do that. So he contacted Babb, Cook & Williard to design him a 64 room georgian style mansion on fifth avenue. The floor plan is that of a typical city dwelling. gThe interiors were done in a french and georgian style The Dining Room and Study The Stair Hall The Main Hall The Library After Carnegie died his widow continued to live there until her death. It was then bought by the Cooper-Hewitt museum which still maintains it today.