The Point Bonita Light is at the entrance to San Francisco Bay. More than 300 boats ran aground near the Golden Gate during the California Gold Rush years. In 1855, a light was installed on a 56-foot (17 m) brick tower at an elevation of 304 ft (93 m). However, the notoriously dense fog would often obscure the light and render it useless to mariners navigating the Golden Gate. The fog signal and lighthouse were subsequently relocated to a lower elevation at the southwestern tip of Point Bonita in 1877. The new location required the builders to overcome many challenges, including the need for a hand carved, 118-feet long (36 m) hard rock tunnel. A narrow path was carved into the rocky point and a landing platform, with a boom for lifting supplies, was built in Bonita Cove. A railway with a forty-five-degree incline connected the platform to the path, and a steam-powered winch was used to pull small cars filled with supplies and construction materials up the track. The new light could be accessed by foot until 1940 when erosion cut a gap in the trail. In 1954 a suspension bridge was built to span the gap, and this was replaced with a new bridge in 2012. The light was automated in 1981 and was the last manned light station on the California coast. Point Bonita Lighthouse is now part of the Golden Gate National Recreation Area and is run by the National Park Service. Read more here and here. Click here to explore more of Point Bonita and the Marin Headlands.