This large, circular tomb is the final resting place of the first emperor of Rome.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This curious, round temple is the oldest still-standing marble building in Rome.

Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.

For hundreds of years, automatons moving to metallic music have been marking the passage of time.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

Ancient paintings known as the "Sistine Chapel of Cave Art."

The great Italian Renaissance painter was laid to rest here in the Chapel of Saint-Hubert.

This museum preserves over-the-top masterpieces that once qualified artisans for membership into a medieval guild.

Beautiful carved tunnels.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

One of the greatest maze designer’s greatest mazes.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

An atmospheric, medieval-themed book store hides in a 13th-century underground space.

The oldest stone house in Paris was built by its most famous alchemist.

A medieval military street hidden beneath a charming French fishing village.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

The inscribed stone at Kilnasaggart is a remnant from nearly a millennium ago.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

Just another ancient, mysterious Irish stone circle.

These imposing walls and towers look more like the ruins of a fortress than a monastery.