Where commuters walk through remnants of an ancient Greek necropolis.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

This Rhode Island mansion was a stand-in for the exteriors of Collinwood in the original "Dark Shadows" series.

The hallucinogenic center of the ancient world.

Monasteries on rock pillars, once accessible only by frayed ropes.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Ironically this massive termite is the mascot for a company that is acclaimed for killing his kind.

An unexpected Easter egg lurks in the background of a cherub wall relief at the Breakers mansion.

The only surviving fragment of the lost Narragansett Pier Casino.

Mysterious stone tower featured in many alternative histories of the New World.

250-year-old farm now features sculptures, a petting zoo and a hippy-bazaar.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

Instead of solid circles, the stoplights in this northern Icelandic town have glowing red hearts.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

This beautiful, historic church looks like something out of a simpler past.

A sulfuric martian landscape that looks far better than it smells.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

This elegant arc of a waterfall marks a religious turning point.