The world's oldest surviving anatomical theater, where "the dead are pleased to help the living."

Built to repay the sins of the father, this church is home to one of the most valuable works of Western art.

The train platform where Jews were sent to concentration camps is now preserved as a Holocaust memorial.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

An Italian hillside ghost town.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

The oldest of Venice's plague quarantine stations, designed to keep the medieval city safe from disease.

Venice's "Island of the Mad."

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

A student driver's nightmare.

A unique Holocaust memorial tells the personal stories of the Jewish residents exiled from greater Berlin.

A wunderkammer of mysterious objects and stories.

A collection of abandoned typographic signs from Berlin and beyond.

A slice of central Asia in the middle of Berlin.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

Hidden beneath the streets of London is a secret subway that only carried mail.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.