This rare and wonderful bird’s-eye-view of Mt. Diablo and its foothills is cleverly positioned and distorted to stretch from San Francisco to the Sierra Nevada Mountains and even Sacramento. At the bottom of the frame we see the San Francisco waterfront, including the Ferry Building. The Bay Bridge was still decades away, so we see instead indications of ferry routes across the Bay to Oakland, Alameda, and Pt. Richmond.

In the East Bay itself, the line of the Southern Pacific railroad runs along the route of today’s 580 freeway, parallel to San Pablo Ave. Several prominent buildings are illustrated, including Hotel Oakland, Oakland City Hall, Hotel Claremont, and the famous Campanile at the University of California, Berkeley. Decades before the opening of the Caldecott Tunnel, instead we see a “Tunnel Road.” This refers to the 1903 tunnel built above the present location of the Caldecott Tunnel, near the top of Temescal Canyon. “Tunnel Road” started at the top of Ashby Avenue in Berkeley.

The map is part of a promotional pamphlet for visiting Mt. Diablo on a motor tour (the verso includes description and photo vignettes of things to see), and the mountain itself is indeed the centerpiece of the view. Ascending from Walnut Creek is the Mt. Diablo Scenic Boulevard, which takes the intrepid visitor to the observatory and tavern at the summit.

The title of the view makes reference to Mt. Diablo’s important role in mapping the Bay Area and beyond. In 1851 the south peak of the mountain was selected by Colonel Leander Ransom as the initial point — where the Mount Diablo Base and Mount Diablo Meridian lines intersect — for cadastral surveys of a large area. Subsequent surveys in much of California, Nevada and Oregon were located with reference to this point.