The Bay Bridge combines suspension, cantilever, tunnel, and truss constructions in an astonishing 8.4-mile-long structure. Envisioned first in 1872 by the legendary Emperor Norton, the project finally coalesced in the 1920s, although initial studies concluded that the bridge could not be built due to the bay's deep muddy waters and the area's strong earthquakes. President Herbert Hoover, who was also an engineer, took up the cause, and the $80.8-million project began in 1933. It would replace an extensive set of ferries and forever alter the landscape and commerce of the Bay Area. Over the next three years and four months, the underwater and above-water construction continued day and night, with 152,000 tons of steel, a million cubic yards of concrete, more than 70,000 miles of cable strands, and 200,000 gallons of paint. Roughly 6,500 workers built this amazing bridge, and 12 lost their lives in the process.