Standard Oil partner Henry Morrison Flagler saw tourism and real-estate opportunity in St. Augustine during the 1880s. He expanded rail connections and commissioned a luxury winter hotel intended to attract wealthy northern guests. Young architects John Carrère and Thomas Hastings designed the Hotel Ponce de León, built between 1885 and 1887 and opened in January 1888. Its Spanish Renaissance Revival composition used towers, arcades, a landscaped courtyard, and richly ornamented public rooms to create a romantic image of Spanish Florida suited to Gilded Age resort development.

The hotel was among the earliest major American structures built with poured-in-place concrete, using local coquina aggregate, and it incorporated electricity, running water, hydraulic elevators, and modern fire precautions. Louis Comfort Tiffany and associated craftsmen supplied stained glass, mosaics, metalwork, and interior design, while George W. Maynard and Virgilio Tojetti created murals. Seasonal guests encountered elaborate service provided by cooks, waiters, maids, porters, gardeners, and hotel staff, many of them Black residents living under segregation. Flagler's development reshaped land, labor, transport, and racial geography as well as architecture.

Changing travel patterns and high operating costs challenged the resort, which closed during parts of the Depression and served as a Coast Guard training center in the Second World War. It returned to hotel use but finally closed in 1967. Flagler College opened in 1968 with the former hotel as its principal building, adapting guest rooms for residences, offices, classrooms, and student life. The conversion preserved a vast landmark that might otherwise have been demolished while introducing the wear, services, and alterations required by a functioning educational institution.

Ponce de Leon Hall retains original concrete walls, towers, courtyard, rotunda, dining room, mosaic floors, carved wood, murals, and Tiffany glass, but it is not an untouched 1888 hotel. Guest-room layouts and service spaces were adapted; roofs, windows, concrete, decorative finishes, and utilities have undergone major restoration; and fire, accessibility, climate, security, and academic systems are modern. Period furniture and displays do not recreate every hotel room. Public tours enter selected historic spaces, while most of the building remains an active campus with privacy and operational restrictions.

Flagler College owns and maintains the National Historic Landmark, balancing preservation with residence, teaching, events, and guided interpretation. Tour access and conservation closures vary with the academic calendar. Strong interpretation connects architectural innovation and Tiffany decoration with the Standard Oil fortune, railroad expansion, hotel labor, segregation, and St. Augustine's reinvention as a tourist destination. The building's authenticity rests on its exceptional original shell and public rooms, reinforced by transparent explanation of college conversion and restoration. It is a preserved resort adapted to education, not a complete operating Gilded Age hotel.