Rebuilt remains of a temple to Roman god Mithras.

One part local history, 99 parts gruesome haunted house.

A hands-off space for graffiti artists to hone and display their skills.

An unusual round church in London with a Templar past.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

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

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

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

It houses the remains of a 17th-century version of the Titanic.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

Metro station with a claim to rock n' roll fame.

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

From Iggy Pop to David Bowie to Nick Cave, this regal music studio has served some of the all time greats.

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

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

An eerie, derelict amusement park in Berlin.

An alien church provides much needed silence in the midst of a Finland shopping center.

A subterranean house of worship carved right out of the bedrock.

This irregularly shaped sea fortress has defended not one but three different sovereign states.