A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

Apartment complexes built into huge repurposed natural gas tanks.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

The topiary maze at the Habsburg hunting lodge.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

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

This former insane asylum now holds a pathological anatomy museum.

This 50-foot-deep sinkhole created in the 14th century is home to rare plants and fungi.

Ancient mysterious ruts carved in the bedrock.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

This Stone Age solar temple aligns with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

A windswept necropolis carved into the rocks overlooks the "most Portuguese town in Portugal."

Houses are tucked between, on, and underneath giant boulders.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

This statue once earned the distinction as one of the "Three Major Disappointments of the World."

This $62 million dollar temple was erected to house one little dental fragment of religious history.

Singapore's landscaping project is home to 18 incredible Supertrees.