In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

This park is home to well over 100 handmade birdhouses.

Oldest building in California still in use.

Two flush headstones mark the only known graves to be embedded in an airport runway.

A historic canal winds through a unique, swampy landscape.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

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

An underground city of salt.

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

Real bones which are said to have belonged to a Polish dragon.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

An ornate plague column – built to celebrate life – claimed the lives of numerous artisans during its construction.

Steadily reminding Czechia of its past.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

Tourists often confuse this beautifully ornate former cigarette factory for a mosque.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

This monumental work of art symbolizes the coming together of a previously divided city.

One of downtown Berlin's last reminders of its Communist past.

One-time largest man-made structure in the world will be a park in 30 years.

"A hideous albatross in the Hudson River Valley."

This monument on Breed's Hill proves that one of the most famous battles of the Revolutionary War is misnamed.