The Ferry Building has been San Francisco's front door since 1898, its 245-foot clock tower, modelled on the one at Seville's cathedral, visible from the bay before you reach the shore. At its peak, 50,000 ferry commuters passed through daily. Then the bridges came, the cars followed, and the building slipped quietly toward obsolescence.

It survived the 1906 earthquake and fire, saved by water cannons on fireboats, and stood firm again in 1989 when Loma Prieta brought down the Bay Bridge. Resilience like that earns a second act. Today it houses a farmers' market and food vendors good enough to make visiting deliberate.

VoiceMap's tours use the Ferry Building to trace what lies beneath the Embarcadero: Gold Rush ships buried under the landfill on which it stands, and the building's place in unexpected timelines, from the birth of the modern chocolate bar to the reshaping of the bay's shoreline.