The Golden Gate Bridge was a larger-than-life engineering project undertaken against dangerous odds and opened 75 years ago against vehement protests and at the cost of 11 lives.

One of the most astonishing and admired man-made wonders of the world, gracing millions of postcards, featured in countless films, the bridge was not at first welcomed with open arms.

Ferry operators and environmentalists opposed it and many engineers doubted such a daring leap over a treacherous Pacific Ocean strait could be built.

The military worried a collapsed Golden Gate span could block access to the Bay in war time.

Some San Franciscans even fought against it because they thought a bridge might ruin the view, according to historians.

Kevin Starr, author of Golden Gate: The Life and Times of America’s Greatest Bridge, said 2,000 related court cases were filed over nearly a decade.

But Mr Starr said litigation and regulatory scrutiny largely concluded in the 1920s allowed builders to move quickly once bank funding was nailed down in 1932, in an early form of public-private cooperation.

“President Obama talks about shovel-ready projects,” said Mr Starr. “This was shovel ready.”

Building the Golden Gate, at an estimated cost of $6 billion in current dollars, was a Herculean task.

While the idea took hold in the prosperous 1920s, by the time ground was broken, the Depression had left many people desperate for jobs.

“Launched midst a thousand hopes and fears; Damned by a thousand hostile sneers,” was how the head engineer for the bridge, Joseph Strauss, described the bridge in a poem he wrote to mark its completion in 1937. He died less than a year later.

Even the bridge’s arresting dark orange colour was an accident, first used as a primer while designers decided what to paint it. The Navy had argued for black with yellow stripes, to ensure it could be seen in a strait hostile to mariners, with dense fog, heavy winds and strong ocean swells.

In the end, bridge authorities decided they liked the colour – known as International Orange – and stuck with it.

“Its elegance is derived from its structural efficiency,” Paul Giroux, from the American Society of Civil Engineers, said at a panel discussion hosted by San Francisco‘s Commonwealth Club.

“It’s a perfect blend of form and function.”

The sad truth about the bridge is that an estimated 1,400 people have jumped off the bridge to end their own lives, a grim reality brought to the attention of many people with a 2006 documentary film, The Bridge, by Eric Steel.