The mystery of the Putim Ossuary involves a tricorn hat.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

This cliff-face port is considered a masterpiece of mining engineering.

A former mining village that now operates as an open-air museum.

Enigmatic tombs and cave dwellings on the outskirts of a rural village.

This poignant tribute to the White Rose movement showcases artifacts related to the heroic anti-Nazi struggle.

Residing along a busy thoroughfare, this sculpture urges passersby to consider the future.

A hidden gem in the middle of the city's infamous Jewelry Quarter.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

Near Birmingham, England three and a half miles of top-secret tunnels housed a World War II “shadow factory” and a Cold War nuclear bunker.

An abandoned brutalist monument whose history has been lost to the ages.

A forgotten and crumbling Yugoslav monument to the victims of fascism.

A local museum honors the overlooked discoveries of Mary Anning, one of the first professional fossil hunters.

A monument at the site of a decisive battle in the First English Civil War.

"The Donut" was built as part of an expensive, ill-fated engineering endeavor.

A well preserved remnant of the English Civil War.

The final resting place of the great navigator, or maybe his brother.

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

This 11th-century Greek monastery has renowned mosaics and relics of a brutal past.

The former Field Marshall and Minister of War to the Russian Imperial Army.