Perched on a cliff on the central California coast, 50 miles south of San Francisco, the 115-foot Pigeon Point Lighthouse, one of the tallest lighthouses in America, has been guiding mariners since 1872. Its five-wick lard oil lamp, and first-order Fresnel lens, comprised of 1,008 prisms, was first lit at sunset, November 15, 1872. The lens stands 16 feet tall, 6 feet in diameter, and weighs 2,000 pounds. It sits in a lantern room that had been constructed at the Lighthouse Service's general depot in New York before being shipped around the Horn.