Mile Rocks Lighthouse was completed in 1906 on a tiny rock off Lands End in San Francisco to warn ships through a dangerous stretch of water marked by strong currents and heavy seas. The need for a fixed light became pressing after the SS City of Rio de Janeiro wrecked there in 1901 with heavy loss of life. Building the station was exceptionally difficult because of the exposed site and limited space, requiring a massive concrete and steel foundation and an 85-foot steel superstructure. Automated in 1966 and later altered for Coast Guard use, it remains a notable offshore landmark tied to a major engineering effort.

Photo: Wikipedia · Public domain