This fairytale medieval church in Poland originally spent centuries in Norway.

The largest of Denmark's seven mysterious round churches stands on an island in the Baltic Sea.

The world’s largest underground marble quarry is hiding in Vermont.

A memorial to the Potawatomi chief who allegedly ran nearly 150 miles to alert settlers of an impending attack.

This breathtaking monastery was established by Saint Benedict himself 1,500 years ago.

An abandoned, desolate train tunnel that was used during World War II.

Once home to an aristocratic family and a workers' organization, this intricately tiled building now houses a chain restaurant.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

Inmates dig the graves at the largest prison cemetery in the U.S., the final resting place of both cowboys and Indians.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

The large collection of pre-Columbian pottery might make you blush.

An 11th-century mountaintop fortress that played a crucial role in Italy's papal wars is now a vacation rental.

A beautiful ruin of a 14th-century Plantagenet castle built by a medieval mercenary.

It's believed King John of England stayed at this 13th-century castle before riding off to sign the Magna Carta.

This network of narrow, medieval passages has the most delightful name.

Wander among the abandoned ruins of this once-powerful medieval town.

Mosaics created from 11 million cigar bands.

This 1,400-year-old abbey was once a powerhouse for music and intellectualism known across Normandy.

A sobering museum dedicated to landmines and the personnel working to remove them from Afghanistan.

An eclectic collection of thousands of items owned by the sculptor Frederic Marès.

Packed with gear and memorabilia, this museum chronicles the history of skiing and how its rise shaped New England.

Historians and hobbyists head to this former French outpost for the annual Feast of the Hunters' Moon.

This amazing 15th-century mural remained hidden in plain sight for centuries.

The eerie remnants of an ancient forest were hidden under the sand for centuries.