For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

A popular tourist cave with a dark past.

The longest burning light bulb in the world.

The largest collection of two headed animals in the world.

A hard-to-reach oasis in a desolate corner of Death Valley National Park.

These millipedes glow not out of attraction, but as a not-too-subtle warning.

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

A 300-ship graveyard, with a few still visible at low tide.

A monument to the love people have for their pets.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

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

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.

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

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

A whimsical antique shop with a strong air of mystery, filled with items from ages, and what feels like worlds, past.

Its buzzing collection honors vibrator history.

This portion of a lovely Belize beach is infested with (harmless) sharks and rays.

Sloth rehabilitation center in the jungle of Costa Rica.

This popular pilgrimage site offers a hole filled with holy healing dirt.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Artfully arranged bones of 5,800 Austrians.

This museum promotes informed contraception by documenting its often secret past.

Macabre museum devoted to historical Viennese murders.