Five ancient libraries, little changed for centuries, preserve a medieval archive of Quranic lore and civic documents

An architectural relic that survived the hands of time.

The last bastion of Roman presence north of the Alps looms over a German town.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

This Cold War–era fallout shelter was actually a storage facility for the nation's emergency currency.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

Two standing giants remain as a tribute to Luxembourg's metallurgical past.

Statues of a fire-breather, a clown, and a whole performing troupe celebrate Luxembourg's creative side.

This magenta statue commemorates the legendary marriage between a mermaid and the city's founder.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Head underground and take a tour of the city's working sewer system, and see the underground river Senne, which defined Brussels for centuries before being covered in the 19th century.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

French Time Capsule-19th Century home revealed to the public.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

London's smallest police station is barely the size of a phone booth.

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

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

Copenhagen's celebrated theme park and gardens.

Finland's oldest astronomical observatory once played a crucial role in seafaring and timekeeping.

This massive Brazilian church is built like an angular, technicolor pyramid left by Mayans from the future.