Rome's semi-secret peephole vista is also a former Crusader stronghold.

This Quebec estate is home to the elaborate gardens of a self-taught horticulturist.

A historic bridge no one is allowed to cross.

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

This unusual building straddles two countries.

The entire length of the border is marked by a 20-foot-wide slash through the trees.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

The oldest candy store in the world has been selling traditional sweets since 1827.

A stunning medieval castle houses this eclectic, interactive tribute to all things wine.

Brooklyn vintners creating world-class wine in a city not known for its vineyards.

This 14th century wine cellar is home to the oldest barrel-stored wine in the world.

A Christian retreat founded to welcome refugees fleeing from the Nazis during World War II.

These ruins reveal the remarkably intact layout of a Roman marketplace.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

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

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

An alchemist's "magic door" stands in the middle of a Roman park.

The charred, dead skeleton of an oak tree is said to have consoled a dying 16th-century Italian poet.

The Italian revolutionary's legendary wife is portrayed on horseback waving a gun and holding her child in this memorial on the Janiculum.

The sacristy of this church contains remains and relics of members of the Aragonese royal family.