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.

Amsterdam's former hotspot for public executions and dissections.

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

The attic of a four-century-old canal house hides a clandestine church.

The history and future of cannabis.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

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

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The underground sanctuary of a mysterious ancient cult.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Ancient serpentine sacrifice holder that has stood the test of time.