There were plenty of displays, including classic cars that first drove over the bridge and a demonstration of the riveting that pegged the graceful structure together.
There was also a parade of ships in the Bay -- the highlight of which was the USS Nimitz, which with its crew of 3,000 sailors, slipped under the bridge.
The highlight of the festivities will be the fireworks show at 9:30 p.m. The best places to view the fireworks are along the city's north shore, from Fort Point to Marina Green. They will not be visible from the Embarcadero.
For 75 years the Golden Gate Bridge has become more than just a reliable way to cross the Bay. It's a symbol recognized across the country.
"What a man-made, beautiful bridge that is. It's so historic," said Sandy Jandik.
The bridge's International Orange color is famous now, but at the time of its construction, the military actually wanted a different color.
"The War Department -- the Navy branch -- thought that it should be a yellow and black striped configuration," said bridge spokesperson Mary Currie.
The original design by engineer Joseph Strauss was quickly criticized. In 1921, the press dubbed it "the ugly rat trap," Currie said.
The graceful bridge has come a long way since its days on the drawing board. Seventy-five years since opening, it's one of only a few structures in the world that has a fan base.
Organizers have been urging spectators to not drive. The Golden Gate Bridge itself will shut down to road traffic for an hour from 9 p.m. to 10 p.m. for fireworks.
Road closures caused some backups. Traffic on the northbound lane of 19th Avenue into San Francisco was heavy most of the day, and traffic on the Embarcadero was stop-and-go early in the evening.
The Presidio is closed to cars that don't have special passes, and parking lots at Crissy Field and the Marina Green are closed all day.
PresidiGo Around the Park shuttles are operating on an expanded schedule until late at night.
Muni is running between Civic Center and Marina Green with extra service on several routes, and bike parking is available.
Additional ferry service is operating to and from San Francisco, and BART has extra trains ready to provide additional service for spectators.