The most important and best preserved remnant of West Africa's powerful Songhai Empire.

A monument to the more than one million enslaved Africans deported from the port of Ouidah.

This strange statue features a bust of the famous composer plopped atop a woman's body.

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

The world's oldest known salt mine.

The solemn exterior conceals an opulent interior of this 17th century church.

Double spiral staircases are not unheard of, but they are very rare.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

An Austrian house of bones filled with hundreds of intricately painted skulls.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

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

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

One of the world's heaviest musical instruments towers within a popular urban park.

A traditional U-Bahn station in Berlin gets a string of rather untraditional benches.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

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

Gardens representing parts of Asia, Europe, and the Mid East are tucked away among the Soviet-style buildings in East Berlin.

Started as a kitchen garden, now the second largest botanical garden in the world.

This general store is more than a century old and home to various oddities and antiques.

Time travel with sweets across history at this research-based candy store.

A particularly creepy abandoned hospital that sparks interest for lovers of the supernatural.

These unusual rooms on wheels are holdovers from the 1960s.

For nearly a year, General Ulysses S. Grant was based here during the American Civil War.

The only place for a truly presidential dram.