Mount Diablo Meridian Initial Point, California

Mount Diablo, an isolated mound rising above the surrounding valley, east of the San Francisco Bay area, was selected to be the Initial Point for the federal land surveys for northern California and Nevada in 1851. It is one of 37 federal survey points of origin covering the USA (outside of the 13 original colonies), known as Initial Points, selected over the course of 150 years, to anchor newly acquired federal land to the legal and cartographic grid. Mount Diablo has the most elaborate commemorative architectures of all the Initial Points. The building at the top of the mountain, built by the Civilian Conservation Corps in the 1930s, contains a small museum and encloses a monument built on top of the summit. The building itself extends the peak another 45 feet in elevation. A concrete column, built at the same time as the rest of the structure, sits atop the exposed bedrock of the summit and continues through the ceiling to a viewing gallery on the level above where it is topped with a brass plate. The rock of the actual summit is exposed at the base of the concrete column. An opening at the base of the column was provided to allow access to the exact spot from which the survey was conducted, marked now by a copper bolt head left from a 1876 triangulation station.