Turns out, it had just been moved to the California coast.
The fate of the cast iron tower was uncovered last year by lighthouse researchers. Colleen MacNeney reported the find in this month's edition of Lighthouse Digest.
MacNeney tells the Cape Cod Times that it was her most exciting discovery.
Wellfleet historian Helen Purcell says the discovery of the light at Point Montara at the southern end of San Francisco Bay was a genuine shock.
MacNeney says she discovered correspondence that proved the lighthouse, first erected in 1881, had been moved by the Coast Guard from Wellfleet to Yerba Buena, Calif., and eventually to Point Montara.
The lighthouse is still used as a navigation aid and a hostel.