The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

This mesmerizing kinetic sculpture blossoms endlessly in the breeze.

The only museum about the history of dentistry in Canada.

Its columns were all carved from the same white oak tree.

A community-run museum invites visitors to explore Jewish communities before and after the Holocaust.

Two adjoining collections of 19th-20th century physics apparatuses and instruments.

Sited in an Inner Mongolian desert are the remnants of an important trade stop along the Silk Road.

Enormous sandstone towers loom within a Czech forest.

The Renaissance-era courthouse is a relic from the fortified town's centuries of Venetian rule.

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

Now abandoned, the world's first torpedo factory is crumbling into the sea.

This picturesque medieval monastery guards a small trove of historic treasures.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

Longest fortress system anywhere in Europe.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

The remains of a sunken military ship wreck visible through clear water.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

An ethereal glowing blue ocean cave in Croatia.

At the right time of day, sunlight floods through the roof of this cave and illuminates the small pavilion hidden within.

This church carved into the rocks is full of enchanting stone statues.

A semi-abandoned village destroyed by U.S. bombings during World War II dominates the valley of Turano.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

This single-track road rewards brave drivers with stunning Scottish scenery.