This probably wasn't what Mao had in mind.

The hallucinogenic center of the ancient world.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Ancient snack bar of the Roman Empire re-opened.

Go inside to really appreciate this 500-year-old technological masterpiece.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

Once the largest windmill outside of Holland, with enormous 114 foot sails.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

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

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

This shop specializes in oddities and Victorian-inspired wonders.

Since 1973, this block has been home to the most concentrated collection of murals in San Francisco.

One of few lasting examples of the brief octagon craze that developed into folly.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

This massive redwood tree has a hole in the base big enough to drive through.

Two mammoth statues inspired by equally tall tales lure tourists to this roadside attraction.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A young botanist's horticultural vision realized through a lifetime of planting, tending, and collecting seeds.

Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

The longest continuous lava tube in Oregon.

A wall of chewing gum moonlights as collective art.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.