NARRATOR: For hundreds of years, European explorers searched this coastline for California's fabled cities of gold.
And yet, the treasure hunters kept missing the entrance to one of the world's finest natural harbors, the Golden Gate.
It was hidden for so long because this is what explorers would see, a rocky shoreline, turbulent waters, and no hint of an opening.
The bay opens up three miles back from the Pacific.
Its entrance is only a mile wide, hard to spy from the sea.
In fact, it was a land expedition that finally spotted the entrance from nearby hills 230 years after the first Spanish ship sailed by.
A 19th century army captain gave the passage its name, Golden Gate.
Today, anyone entering the bay by sea must pass under San Francisco's most iconic structure, the Golden Gate Bridge.
It's hard to imagine now, but before the bridge was built, the only way across the bay was by ferry.
Boats carried 50,000 commuters a week.
