The 1.7-mile-long Golden Gate Bridge, an icon of the San Francisco Bay region, connects the city of San Francisco to Marin County, California. At its completion in 1937, the suspension bridge was considered an engineering marvel—the longest main suspension bridge span in the world. It held that record until New York City's Verrazano Narrows Bridge opened in 1964 and, as of 2019, the Akashi Kaikyo Bridge in Japan boasts the world’s longest span.

Today, the West Coast landmark draws millions of commuters—and tourists—each year. Here are eight historical and surprising fast facts about the Golden Gate Bridge.

In June 1935 an earthquake struck the region as men worked atop the bridge's unfinished south tower. According to PBS' American Experience, one worker recalled, "the tower swayed 16 feet each way. There were 12 or 13 guys on top with no way to get down... The whole thing would sway toward the ocean, guys would say, 'here we go!' Then it would sway back toward the bay."

During construction, a safety net was suspended under the floor of the bridge, extending 10 feet wider than the bridge’s width and 15 feet longer than its length. The net proved an invaluable precaution as it saved the lives of 19 men. These men became known as members of the "Half-Way-to-Hell Club." Despite such safety measures, 11 men died during the bridge's construction.

The U.S. Navy had lobbied that the bridge be painted in blue and yellow stripes to increase its visibility. But when the steel arrived in San Francisco painted in a burnt red hue as primer, the consulting architect decided the color was both highly visible—and more pleasing to the eye. The bridge's color is officially called international orange.

San Franciscans celebrated the opening of the Golden Gate Bridge with Pedestrian Day on May 27, 1937. As many as 200,000 people crossed the bridge that day. People competed to be the first to run, push a baby stroller, and even roller skate across the Golden Gate Bridge.

The San Francisco Chronicle recorded some of the more outlandish firsts, including the first person to cross the Golden Gate Bridge on stilts. The bridge opened to vehicular traffic the following day.

The initial toll for the bridge was 50 cents each way—roughly equivalent to an $18.00 roundtrip today—a hefty price to pay in the midst of the Great Depression. Today, Golden Gate Bridge tolls are collected in one direction only, heading southbound into the city of San Francisco.

San Francisco celebrated the 50th anniversary of the Golden Gate Bridge on May 24, 1987, with a bridge walk. The bridge began to groan and sway with an estimated 300,000 people packed like sardines onto it. The middle of the bridge sagged seven feet under the unprecedented weight, causing the iconic arch to flatten.

Officials quickly closed the bridge, preventing an additional 600,000 people from crossing. Engineers afterward said that the bridge, which was built to bend, was never in danger of collapsing.

The Golden Gate Bridge’s fog horns, mounted at the middle and south tower (San Francisco side) of the bridge, may be nearly as iconic as the structure itself. The San Francisco Bay is famously foggy, and the bridge may have a slight influence on directing the flow of the fog as it pushes up and pours down around the Bridge. Each horn emits a different tone at different times to help guide ships safely through dense fog.

During March, the fog horns may be heard for less than half an hour a day, though during the summer—San Francisco’s foggy season—they may blare for five or more hours for days at a time. The two fog horns, on average, sound for an average of 2.5 hours each day throughout the year.

The color of the bridge, officially called international orange, was chosen in part because of its high visibility in fog.

In the 1930s, the Golden Gate Bridge was coated with a primer that was two-thirds (by weight) lead. The architects intended the lead-based paint to protect the steel structure from corrosion but later learned that lead is harmful to humans and the environment.

A massive cleanup effort to remove all the lead-based paint from the bridge started in 1965 and ended in 1995. Today, zinc-based primer paint is used instead. The Golden Gate Bridge Highway and Transportation District calls zinc a “sacrificial metal” that protects the steel from rust.