The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A monument to the man who almost killed Hitler.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

One of downtown Berlin's last reminders of its Communist past.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

Most prolific publishing house in the 1600s open to the public.

An open-air sewer system that was covered piece-by-piece over 300 years.

Famously misunderstood wonder of the ancient world

A statue marks the exact spot where The Boy Who Never Grows Up made his first literary appearance.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

Monument to a suicide protesting the Soviet invasion.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

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

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

The wooden telephone box hidden away in London's Piccadilly was the original prototype of the iconic kiosk.

The taxidermied remains of a once-great parrot.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

This one has sailed five times as far as Sir Francis Drake's famous ship.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

Scattered throughout London are ancient remnants of the city's former bounding wall.

The anatomical-pathological collection of a man who changed surgery.