Interesting facts about the bridge. Bridge San Francisco Bay and connects with Oakland and East Bay. Work started 1933, date and completion 1937. Total length of bridge 4 1/4 miles. Longest span 2,310 feet. High tower 518 feet above water. Number of piers, 51. Steel used, 200,000 tons. Cables, 28 3/4 inches in diameter. Wires in each cable, 17,464. Total mileage of wires in cables, 70,800 miles. Concrete used, 1,000,000 cubic yards. Upper level provides six automobile lanes. Lower level three lanes for heavy traffic and two interurban lines. Total cost, $75,000,000.