The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Beloved children's TV characters freckle the German city's streets.

This historic stone bridge has an entire neighborhood clinging to its sides.

The haunting complex honors the millions of Ukrainians who died in the forced famine under Soviet rule.

The first museum in the world devoted to sexual gadgetry.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

Steadily reminding Czechia of its past.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

The hidden lair of an alchemist rediscovered in a 2002 flood.

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

A surreal statue honoring Prague's favorite literary son.

Macabre astrological automaton clock dating to the late 1400s.

This Ukranian fortress is one of the best-preserved medieval castles in Europe.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

This hidden fortress has been coined the "City of Ghosts."

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

This snug medieval lane is one of the narrowest streets in the world.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This easily overlooked memorial immortalizes the scars from the 1956 Hungarian Revolution.

The geographical center of Budapest is marked with a 10-foot-tall stylized zero.