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

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

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

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

Eighty million natural history specimens call this gargantuan museum home.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

A fascinating insight into daily life in the Eastern Bloc.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A museum in the childhood house of a medical pioneer.

Once the home of a hermetic monk, this cave now houses a small church.

Museum dedicated to the terror regimes of Hungary.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

Real bones which are said to have belonged to a Polish dragon.

An underground city of salt.

Plaques celebrating Lithuanian writers freckle a wall of this picture-perfect path.

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

An abandoned masterpiece of Soviet Brutalist architecture.

While this monument tile is shrouded in mystery it also marks the end of the longest ever human chain.

The Frank Zappa fan club erected this monument to their prog-rock hero to mark a new era of post-Soviet Lithuania.

Legend has it that Napoleon Bonaparte fell in love with this Gothic church.

A small monument in Lithuania marks the geographic center of Europe—or at least one of the claimants.

Open-air museum with a large collection of Soviet-era statues.