Northern Ireland's Brobdingnagian stepping stones.

Where commuters walk through remnants of an ancient Greek necropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Tiki luxury on Nob Hill.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

Erotic art covers the walls of the largest ancient pleasure palace.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.

Roman ruins, natural methane fires and a lovely beach.

This private residence was the template for one of the most beloved television homes of all time.

San Francisco's oldest surviving monument and meeting place for 1906 survivors.

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

An essential stop before plundering, BYO Cutlass.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

Furniture tries to escape an abandoned building in San Francisco.

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

This stoic, if derpy, giant stands as a monument to Oregon's statehood and the novelty culture of yesteryear.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

The magic's in the hole!

Macabre astrological automaton clock dating to the late 1400s.