A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

Black cat statues guard this temple-like Egyptian revival factory.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

An early work of the architect Álvaro Siza Vieira, these swimming pools blend into the beach.

A hidden three-foot-wide house separates these two regal churches.

Elaborate tile work in this railway station tells the story of Portugal.

The stunning interior of this Gothic church is covered in ornate gold details.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Tiny memorials honor individual victims of the Holocaust.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

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

The most visited, and possibly most controversial, museum in Germany.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

This automated sculpture of two men peeing will spell out text messages with their micturition.

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

Macabre astrological automaton clock dating to the late 1400s.

A Swiss board game museum housed inside a picture-perfect castle.

Swiss vineyards in a UNESCO heritage site.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.