Flagler Museum, also known as Whitehall, is a 55-room mansion open to the public in Palm Beach, Florida in the United States. The building is a National Historic Landmark.
Henry Flagler, one of the founders of Standard Oil, built Whitehall for his third wife, Mary Lily, in 1902. The architects were Carrère and Hastings. It was originally intended as a winter residence, and Henry gave it to Mary as a wedding present. They would travel to Palm Beach each year in one of their own private railcars, one of which (#91), was restored to its original 1912 condition and is sitting outside the museum.
The building was used as a hotel after 1925 and was saved from demolition by one of Henry Flagler's granddaughters Jean Flagler Matthews. Her father, Harry Harkness Flagler, had died in 1952 leaving her a large Standard Oil inheritance. She established the Henry Morrison Flagler Museum corporation which purchased the building in 1959, opening it as a museum in 1960.