A haunting collection of the vanished and disappearing natural world.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

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

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

A Hungarian pharmacy museum with a box full of mummy powder.

Budapest's Communist-era statues, banished to the suburbs.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

Once the home of a hermetic monk, this cave now houses a small church.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

The house that took a plunge into the facade of a museum.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.

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

Museum devoted to the artificial language of Esperanto.

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.

The resting place for anonymous victims of the Danube's dark waters.

The topiary maze at the Habsburg hunting lodge.

A spherical "micro-nation" in the heart of Vienna.

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

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

The final resting place for the remains of 143 Habsburg royalty.

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