The 98-meter arch over Fort Point at the south end of the Golden Gate Bridge. A fort guard tower is at the bottom of the picture.
The bridge was designed to meet 1930s seismic standards, which were believed to resist a major earthquake. But an analysis after the 1989 Loma Prieta earthquake determined that weaknesses in this arch would actually cause the entire bridge to collapse in an earthquake. A $392-million retrofitting project began in 2001. Scheduled for completion in 2012, the upgrade should allow the bridge to survive an 8.3-magnitude shock with minimal damage.