A major engineering feat of the late 1800s, Spectacle Reef Lighthouse was constructed at the eastern end of the Straits of Macinac, ten miles east of Bois Blanc Island on Lake Huron. The reef was more dreaded by navigators than any other unmarked danger throughout the entire chain of Great Lakes. The lighthouse took four years for a work force of two hundred men to build at the exorbitant price, at that time, of $406,000. Lighted for the first time in June 1874, its lamp today shines at four hundred thousand candlepower and has guided lake vessels past the dangerous reef into Lake Michigan for over a century.