Giant topiary dog once played a role in a terrorist bomb plot.

Historic medieval fortified city in southwest France.

The curious underground history of keeping Paris clean.

A beautiful and classically designed villa, with an hourly infestation of monsters.

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

The celebrated eyesore created by starry-eyed sweethearts.

Human ancestor’s 3.6 million year-old footprints.

Jesus' footprints and the first catacombs in the world.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Pilgrimage site for star-crossed lovers.

Water and windows define this defensive Italian well.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

The largest and most famous wax anatomical collection anywhere in the world.

Bridge that died in war and was resurected.

Longest fortress system anywhere in Europe.

An ancient knight and a symbol of the city's freedom.

Gargoyle head that brings good luck.

Huge winged monument in the United Kingdom.

Catacombs turned marketplace.

The mummified right fist of a 1,000-year-old saint-king sits inside an ornate golden reliquary.

Museum dedicated to the terror regimes of Hungary.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Museum dedicated to the UK's first charity for abandoned children, with keepsakes of the mothers who left them behind.