A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

This mysterious and once-grand memorial still embodies a remarkable architectural vision.

A mysterious concrete hand reaches out from between the stones of Uniwersytecki bridge.

In the center of Wrocław's old meat market stands a somber tribute to the city's livestock.

A collection of old neon signs from all over Poland line a secluded courtyard.

A 90-ton, gravity-defiant steam locomotive shoots for the skies in this bizarrely beautiful public artwork.

The silly symbol for an underground protest group is now scattered around the city.

A striking public sculpture representing the period of martial law in Communist Poland.

This oddly beautiful water cistern is a techno-temple to the wet stuff and a multimedia masterpiece.

Legends surround an ancient tree trunk riddled with nails for good luck.

One of Vienna’s oldest (and perhaps most haunted) alleys, allegedly with a bloody past that gave it its name.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.

Designed as a reminder of one of the darkest moments in Austrian history.

Along the edge of this fountain are 365 smaller fountains that represent the days of the year.

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

A literary park dedicated to the memory of a filmmaker, writer, and intellectual who was killed in 1975.

Roman-era ships unearthed...

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.

A fairy tale castle in modern Rome.

Architectureal fantasy quarter of Rome.

Romans decided this 16th-century "talking statue" was so ugly, they named it after a primate.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

Architectural monsters are devouring this palace's every door and window.