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

The celebrated eyesore created by starry-eyed sweethearts.

This demon atop the Notre-Dame de Paris looks utterly bored.

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

Claude Monet was baptized in this lavishly ornate Paris church.

The oldest and smallest cemetery in Paris is only open to the public twice a year.

Unfortunately, you can no longer spend a night in this single-person treetop hotel.

This 2,000-year-old stone maze is one of the oldest in the country, but its purpose is still a mystery.

This patch of land is home to Sweden's largest burial mound, allegedly belonging to a mythical king.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

Celebrated example of Ottoman architecture that also served as a site for brutal massacres.

For over 40 years, this quaint little house has teetered on a rock in the middle of a river.

An idyllic traditional timber village on a picturesque hill was built for a film.

Through the colossal entrance to this cave you'll find limestone tubs and an underground waterfall.

This spaceship-like Serbian monument reaches for the stars in celebration of the fallen fighters of fascism.

Near Belgrade, an ancient-looking sarcophagus serves as a World War I monument.

Different sections of the Zemun Fortress were built in the 14th and 15th century as a response to the advance of the Ottoman Empire.

Considered an architectural abomination by some, this metal-clad building is known as 'little red riding hood' by locals.

A pair of connected skyscrapers form this symbolic gateway.

A retro Yugoslav congress, cultural, and business hall built in the 1970s, with an iconic world clock.

A Serbian church lit by chandeliers made of weapons.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

Arguably Belgrade's only example of pure Art Deco architecture.

One of Belgrade's most beloved animals.