California State Railroad Museum sits in Old Sacramento looking rather pleased with itself, and no wonder: it houses more than twenty beautifully restored locomotives and cars inside a 100,000-square-foot hall, each engine gleaming as though it had never once hauled coal. Its real subject, though, lies just outside its doors.

A few streets away, at the foot of K Street, workers broke ground on America's first transcontinental railroad in January 1863, while the Civil War raged back east. Between April and October, a steam train still pulls visitors along the Sacramento River.

VoiceMap's self-guided bike tour of Gold Rush Sacramento rolls past the museum's red brick facade en route to the Sacramento Valley Station mural and the Theodore Judah monument, explaining why the engineer who surveyed the route faded from memory while the investors he recruited got universities and districts named after them instead.