This is Flagler Museum, also known as Whitehall It is a 55-room mansion built by Henry Flagler in 1902, and is now open to the public.

Henry Flagler was an American industrialist and a founder of Standard Oil. He was also a key figure in the
development of the eastern coast of Florida along the Atlantic Ocean and was founder of what became the Florida East Coast Railway.
He is known as the father of Miami, Florida and also founded Palm Beach, Florida