The eroded core of an ancient volcano is now accessible by a short hike.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Ancient pueblos built into the base of a natural canyon wall.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

This famous bridge twisted itself into oblivion, but not for the reason you might think.

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

A curious collection dedicated to human and animal anatomy and pathology.

A public urinal so pretty, it was declared a national monument.

Established in 1638 to battle the Black Death, this botanical garden is a treasure trove of rare flora.

The former headquarters of history's oldest megacorporation.

The history and future of cannabis.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

Amsterdam's former hotspot for public executions and dissections.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

A unique work of automotive art calls this shopping center home.

Museum preserving torture methods from the past.

Abandoned bull fighting ring, slowly falling apart in Uruguay.

Constructed on the ruins of a convent, this tower saved countless lives.

The scars of World War II are preserved on its walls.

This poignant tribute to the White Rose movement showcases artifacts related to the heroic anti-Nazi struggle.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

This magnificent museum claims to house the cranium of a disciple and the skull of a pope.