Frederick Bourne commissioned Ernest Flagg, a New York City architect, to design a castle hunting lodge on Dark Island. Bourne stipulated that the structure was not to imitate any existing castle. Flagg had recently read Woodstock by Sir Walter Scott which was set in “The Towers”, a hunting lodge castle used by royalty near Woodstock, England. Flagg incorporated descriptions of the book’s castle, torn down in the early 1700’s to design Bourne’s castle – complete with towers, turrets, secret passageways, and underground tunnel, and even a turret dungeon. Construction began in the spring of 1903 and involved 100 masons. Granite was quarried from Oak Island and sandstone came from the quarry in Hammond. The castle was completed and first used in the fall of 1905. The castle contains 28 rooms, 10 fireplaces and 8 bathrooms as well as 2 boathouses, 2 ice houses, a skiff house, and a bath house. There are passageways throughout the castle and each passageway entrance is hidden or blended in the walls and has a mechanical and an electrical means of opening.