Guns that have been defending San Francisco since 1904.

Ride the subways of yesteryear.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

Upside-down trees serve as natural flower pots in this hanging garden of Alaska.

This legendary "evil" doll has been haunting the citizens of Key West for over 100 years.

Small island science organization offers public the chance to participate in research.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

A tunnel of hardened lava along Maui’s famous Road to Hana.

Site of a former hidden treehouse in New Orleans.

A modernist landscape of water and sci-fi concrete.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Where Nor'easters go to die.

A giant Troll lurks under one of Seattle's oldest bridges.

An antiquated German apothecary on Chicago's North Side.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

Towering basalt columns, a creation of fire and ice.

A hot dog stand where the heads are just as hot as the dogs.

A beautiful geyser under environmental threat.

The most confusing clock in New York.

A wall of chewing gum moonlights as collective art.

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

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

Less a museum than a bizarre fantasy world created by artists and engineers.