The original San Francisco City Hall, completed in 1899 after twenty-seven years of construction delays and corruption scandals, was destroyed in the 1906 earthquake. The replacement, designed by Arthur Brown Jr. and John Bakewell Jr. in the Beaux-Arts style, opened in 1915 as the centerpiece of the new Civic Center. Brown had studied at the Ecole des Beaux-Arts in Paris, and his design reflects that training: a grand rotunda, sweeping staircases, marble floors, and enough gold leaf on the dome to make it gleam on overcast days. The building occupies two full city blocks and contains the mayor's office, the Board of Supervisors chambers, and numerous city departments.

On that morning, former Supervisor Dan White entered City Hall through a basement window to avoid the metal detectors at the main entrance. He walked to the office of Mayor George Moscone, shot him twice, then crossed the building to the office of Supervisor Harvey Milk, the first openly gay elected official in California, and shot him five times. Both men died. White was convicted of voluntary manslaughter rather than murder, a verdict that provoked the White Night riots in the Civic Center. The assassinations transformed San Francisco's political landscape and made Harvey Milk a symbol of LGBTQ rights worldwide. A bust of Milk now stands in City Hall.

On February 12, 2004, Mayor Gavin Newsom directed the county clerk to begin issuing marriage licenses to same-sex couples, making San Francisco the first jurisdiction in the United States to do so. Over the next month, approximately 4,000 couples were married at City Hall in what became known as the Winter of Love. The California Supreme Court later voided the marriages, ruling that Newsom had exceeded his authority. But the images of jubilant couples on City Hall's grand staircase galvanized the national marriage equality movement. When the U.S. Supreme Court legalized same-sex marriage nationwide in 2015, City Hall was illuminated in rainbow colors.

City Hall underwent a $300 million seismic retrofit and restoration completed in 1999, installing base isolators that allow the building to ride out future earthquakes. The restoration brought back architectural details that had been obscured or damaged over the decades, including the ornate light fixtures and decorative metalwork. The grand staircase and rotunda remain popular venues for weddings, political events, and public gatherings. From outside, the dome dominates the Civic Center skyline, flanked by the War Memorial Opera House, Davies Symphony Hall, and the Asian Art Museum. Inside, the building's scale is deliberately imposing: the rotunda soars overhead, the marble echoes, and the grand staircase forces visitors to climb toward the offices of power. Brown designed it that way. Democracy, he believed, deserved architecture that made people look up.