Artist Leo Villareal turned on his work at 9 p.m., flipping the switch for 25,000 LED lights attached to the bridge cables, the Contra Costa (Calif.) Times reported. Bay Lights, on the bridge's western span, has lights that pulse randomly.
Thousands of people watched from the shoreline in Oakland and San Francisco, from cruise boats and from bars and restaurants with a bridge view.
"I'm planning to come back," San Franciscan Zehra Ashraf said. "I don't think I'll get bored with these repeating patterns."
Her friend Mohit Aggarwal said the lights "add a scenic and cerebral element to the city."
Bay Lights will be visible from dusk to 2 a.m. for the next two years. The $8 million project is being paid for from private sources.
2014: The Year in Music [PHOTOS]