The deadliest diving spot in the world is also a stunning geological marvel.

A lover's walk between hilltop towns, decorated with graffiti love notes.

A sunken idol welcomes parishioners to Davy Jones' Locker.

Massive galleon from a box-office bomb docked in Genoa.

The fairy tale castle of the "fairy-tale king."

The prototype for all Nazi concentration camps.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

Museum preserving torture methods from the past.

Budapest's Communist-era statues, banished to the suburbs.

Museum dedicated to the terror regimes of Hungary.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

The 340-year-old house that inspired the classic Nathaniel Hawthorne novel.

Statue in Salem of the woman who starred as the witch Samantha in the sitcom "Bewitched."

The only structure left with direct ties to the Salem witchcraft trials of 1692.

This landmark cemetery in Boston was created more than 300 years ago.

No one messes with the Massachusetts sacred cod, not this time...

The tomb of Increase Mather and his son Cotton, influential colonial ministers obsessed with the occult.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

Rome's semi-secret peephole vista is also a former Crusader stronghold.