In the mid-1930s, two familiar spires towered above the morning fog.
Stretching 227 meters into the sky, these 22,000-ton towers would help support California's Golden Gate Bridge.
But since they were currently in Pennsylvania, they first had to be dismantled, packaged, and shipped piece by piece over 4,500 kilometers away.
Moving the bridge's towers across a continent was just one of the challenges facing Charles Ellis and Joseph Strauss, the project's lead engineers.
Even before construction began, the pair faced all kinds of opposition.
The military feared the bridge would make the important harbor an even more vulnerable target.
Ferry companies claimed the bridge would steal their business, and residents wanted to preserve the area's natural scenery.
Worse still, many engineers thought the project was impossible.
The Golden Gate Strait was home to 96-kilometer-per-hour winds, swirling tides, an endless blanket of fog, and the earthquake-prone San Andreas fault.
But Strauss was convinced the bridge could be built; and that it would provide San Francisco's commuters more reliable passage to the city.
