The Oakland Bay Bridge in San Francisco boasts more superlatives than any bridge on earth. Bridge builders of the depression era defied logic and economics and succeeded in building an 8 mile long structure connecting Oakland and San Francisco. Engineer Charles Purcell built two suspension bridges side by side on the San Francisco side of the bay, then built the largest bore tunnel in the world to connect the west side with Oakland’s eastern shores. Modern Marvels shows you how this great feat was accomplished.