A fortress on this island housed the mysterious prisoner known as the "Man in the Iron Mask" for more than a decade.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

The bar where "The Great Train Robbery" was planned was once a nexus of high society and low morals.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

London's old-school healing garden.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

An unusual round church in London with a Templar past.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

"There's nothing there," and other lies the KGB told us.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

A small island dotted with old, historic Finnish buildings.

A subterranean house of worship carved right out of the bedrock.

Inside this small chapel tucked away in the forest is one of the most well-preserved Danse Macabre frescos.

This heart-shaped island looks substantially less lovely after a recent bulldozing project.

This abandoned Croatian stronghold never saw a great deal of conflict but it is still a beloved relic nonetheless.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

Humble beginnings for one of the world's most famous scientists.