A museum in Hokkaido is housed in a former high school. On its grounds a marker shares the awakening of a man who longs to be reunited with his soulmate in the fictional world of Kcymaerxthaere.

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

A magical place that lets you play in and explore the world of Studio Ghibli.

A spectacular Bulgarian cave resembling a devil's head with a waterfall rushing down its throat.

An abandoned factory along the Mississippi coated by a giant mural.

A spring-fed pool so deep it's used for scuba diving as well as swimming.

This former Cyprus flight hub is now a crumbling, abandoned ghost complex.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This former Welsh metal factory is now a lovely abandoned relic but was once one of the industry's world leaders.

This German monument honors the so-called "Prince of Mathematicians."

Hauled from the water's depths, Henry VIII's flagship is preserved in this capsule-shaped museum.

This ancient sinkhole-turned-healing-pool is a treasure trove of archeological discoveries and may even be the Fountain of Youth.

A once grand hotel is being retaken by the wilderness it once capitalized on.

A gorgeous medieval library where the books are kept in chains.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Town full of spiritualists, some of whom are mediums, is still in full swing after 130 years.

The abandoned Bermudian home of a British naval leader is surrounded by crumbling sporting fields and the graves of convicts.

These magnificent 240-year-old machines are considered distant ancestors of the computer.

A 16th-century horror show built in a lovely Italian garden.

This spa theme park lets its guests take a dip in pools of coffee, wine, or ramen broth.

The last remnants of what was once one of the world's grandest hotels can now be found in a Manhattan subway station.

An indigenous take on European design creates a stunning visual overload.

Monuments don't get much more metal than these three giant viking swords planted in a Nordic hill.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.