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

Olfactory delights in San Francisco's Botanical Gardens.

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

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

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

A winding path built in secret on the edge of the continent.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A 140-year-old castle with underground caves hidden in San Francisco.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

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

This often-overlooked ocean walkway was once considered an impossible fantasy.

These sacred Mesoamerican ruins feature peculiar petroglyphs hidden in the stones.

An incredible collection of Mesoamerican art assembled by one of Mexico's great artists.

The ruins of an abandoned church mingle with the graves at Oaxaca’s General Cemetery.

A 16th-century monastery boasts a lush array of plants native to Mexico’s most biodiverse region.

A 19th-century Baja cantina that many say is the birthplace of the margarita.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

One of the few places in the world home to living stromatolites.

Dine aboard the historic Ghan train while retracing early explorers' journey through the Outback.

An opal mining town in the middle of Australia where people live, worship, and shop underground.

Alien rock formations grown from the sands of an Australian national park.