The Golden Gate Bridge was an engineering marvel. The site alone -- buffeted by high winds and split by the swirling currents of the Golden Gate -- made construction treacherous. The sheer size of the bridge (the longest suspension bridge in the world until the Verrazano-Narrows Bridge opened in 1964) required several innovations in bridge-building technology, especially where it came to constructing the two colossal anchorages in -- and under -- turbulent water.
Of all the mind-boggling statistics surrounding the bridge's construction, and there are plenty, perhaps the most jaw-dropping involves the two main suspension cables. Each measures 7,659 feet in length and each used hundreds of pencil-thick wires bound together to make a cable just over three feet in diameter. In all, more than 80,000 miles of steel wire was needed, enough to circle the earth three times.
(image credit: jeromeinsf)