Built primarily in the last quarter of the 19th century and the first decade of the 20th century, the FEC was a project of Standard Oil principal Henry Flagler. He originally visited Florida with his first wife, Mary; they sought assistance with the health issues she faced. A key strategist who worked closely with John D. Rockefeller building the Standard Oil Trust, Flagler noted both great potential and a lack of services during his stay at St. Augustine. He subsequently began what amounted to his second career, developing resorts, industries, and communities all along Florida's shores abutting the Atlantic Ocean.