Which sculpture did Bono graffiti in San Francisco?

During a free performance by U2 to 20,000 people in San Francisco’s Justin Herman Plaza on November 11th, 1987, lead singer Bono spray painted “Stop The Traffic” and “Rock N Roll” on the Vaillancourt Fountain. Footage of the act can be seen in the band’s 1988 concert film, Rattle and Hum.