Sea Gull Cottage was constructed in 1886 overlooking what was a freshwater lake (now the Intracoastal Waterway) by RR MCCormick, the Denver railroad and land developer. This was Flagler's first Palm Beach residence after he purchased it in 1893. It is the oldest house on the island, although it used to be located next to the Royal Poinciana Hotel, Flagler's first resort hotel in Palm Beach. It was moved to its current site for preservation in 1984.

　　Built in the Florida vernacular style, the shingle cottage was famous as the 'showplace along the shores,' so pretty was its stained glass windows, Georgian marble floors and commanding viewing turret. You can't enter the building, but it's worth viewing its exterior in any case.