An enchanting tunnel of cypress trees leads to an old morse code station still used today.

Its dark depths conceal millions of rare, delicate crystal formations.

Founded in 1873 to support the needs of the gold mines flourishing nearby, this is the last water-powered foundry in the United States.

One of the oldest reform schools in the United States, home to wayward boys such as Merle Haggard, now abandoned.

This 19th century hydroelectric powerhouse was the first of its kind.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Golden Gate Park's historic collection of plants.

A huge musical instrument played by the ocean.