A mysterious set of tunnels carved in the hills of rural northern Kyushu.

Once the most densely populated place in the world, this island is now a ghost town.

The magical, mossy forest that inspired Princess Mononoke.

A Turkish ghost town abandoned in a population exchange with Greece.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

An ancient Viking village in North America that predates Columbus by 500 years.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

On Japan's Tashirojima Island, cats are king.

This remote British Imperial telegraph relay outpost drove men insane.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

An ancient Egyptian temple in the middle of Madrid, Spain.

Hoax, mistake, or evidence of dinosaurs in human times?

Ruins of a German Castle on top of a towering stone pillar.

A battle between nature and architecture in the Cambodian jungle.

One of Scotland's most important modern structures, it just made the '100 Most Endangered Sites' list.

These azure waters were thought to lead to the Mayan Underworld.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

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

The remains of a ruined mansion memorialize the 1906 earthquake.

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

The ancient tomb acts as a calendar that keeps perfect time.