Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

Tenacious mummies survived dental problems, eternal entombment, and more than their fair share of devastating fires.

Another of California's unused Cold War missile defense complexes has become a graffiti gallery.

A rough granite monument marks the spot where Europeans first caught sight of the San Francisco Bay.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

This free, take-a-book shop seems like a trick but isn't.

This abandoned boat was left in place thanks to its rotting beauty.

Longtime headquarters of controversial boys' club for the world's wealthiest and most powerful.

The stones that traveled from Spain to eventually become a holy place for San Francisco's nature worshippers.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Its buzzing collection honors vibrator history.

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

Visible below the waves are memorials to the city's Gold Rush dead.

The only theatre in the world constructed specifically for sound movement.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

A library built during San Francisco's pioneer times is a student's retreat, bibliophile's sanctuary, and chess player's delight.