This modest marker near Notre Dame identifies the very center of Paris.

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

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

One of England's most famous churches hides a pair of little known architectural treasures.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

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

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This Polish cave has housed a dragon, a brothel, and an enduring legend.

The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

This antique thermometer honors the creator of the first universal temperature scale.

A huge wooden clock that is so beautiful its creator was forcibly blinded.

Relive a Polish uprising via an enormous, century-old cyclorama.

The silly symbol for an underground protest group is now scattered around the city.

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

The secular incarnation of a religious meditation.

This legendary city has been a tourist attraction for centuries.

A spectacular cave and a beguiling lake.

The hallucinogenic center of the ancient world.

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

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

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A Hungarian pharmacy museum with a box full of mummy powder.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

A museum in the childhood house of a medical pioneer.