San Francisco — from 1,000 residents to 25,000 in eighteen months

San Francisco began life as a Spanish mission and presidio, both founded in 1776: the Mission San Francisco de Asís, better known as Mission Dolores, and a military garrison guarding the entrance to the bay. For seven decades it remained a quiet outpost of a few hundred people — renamed San Francisco in 1847, still barely a village. Then, in 1848, gold turned up at Sutter's Mill. Word spread, and by 1849 the town's population had rocketed from roughly 1,000 to 25,000, a nearly 3,000 percent increase in under two years, as prospectors from around the world funneled through its port on their way to the goldfields.

That boomtown energy shaped the city's infrastructure decades later, too. In 1873, engineer Andrew Hallidie tested a cable-powered streetcar on Clay Street, designed to conquer hills too steep for horse-drawn carriages — the system that still runs today as the only moving National Historic Landmark in the country. And in 1937, the Golden Gate Bridge opened in a colour nobody expected: architect Irving Morrow chose International Orange over the US Navy's proposed black-and-yellow stripes, reasoning it would stand out against the fog and complement the surrounding hills rather than clash with them.

What the three cameras show

San Francisco beyond the webcams

Golden Gate Bridge: the 1.7-mile International Orange suspension span connecting the city to the Marin Headlands.

Mission Dolores: the 1791 adobe chapel, the oldest intact building in San Francisco, part of the original 1776 mission.

Cable cars: the Powell-Hyde, Powell-Mason and California Street lines, running on Hallidie's 1873 system.

When to watch

Late afternoon, clear skies: for the fog rolling back off the bay and the clearest views across the hills.

Getting there: San Francisco sits on a peninsula between the Pacific Ocean and San Francisco Bay, California, USA.