An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

France's most famous cemetery, with some of its most curious tombs.

The oldest continuously operating pharmacy in Europe.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

This memorial to the victims of the Romanian Revolution of 1989 is often compared to a potato on a skewer.

Romania's triumphal arch looks out over Bucharest.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

Something's watching you.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This massive underground salt mine now holds a sci-fi theme park in its depths.

Longest fortress system anywhere in Europe.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

A tiny church on a man-made island in the Adriatic.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

340-foot statue built to honour the Heroes of the Soviet Union.