These curious caverns have been home to mushrooms, gangsters, and disco.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

In Costa Rica's cloud forest, the roots of a woody ficus create a botanical bridge.

A secret climbing tree hides along the side of a Costa Rican road.

Ride a dragon train into a world of dwarves.

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

Visiting this café is like visiting the Austrian grandma you wish you had.

An ornate private entrance to the Vienna subway built specifically for the emperor.

The housing complex served as an anti-fascist fortress during the Austrian Civil War.

Inside the corridors of this flea market, visitors are sure to find some obscure and odd treasures.

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

A silly medieval mural preserved on the side of a Viennese house.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

This museum promotes informed contraception by documenting its often secret past.

Baroque celebration of the end of the Great Plague of Vienna.

Dine amidst exotic plants at this former royal greenhouse.

Op-art architecture designed for happiness.

This cubist Vienna church building looks like some sort of alien stonehenge.

Located right outside of Vienna, visitors can take in expansive views of an ethereal forest.

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

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

This former insane asylum now holds a pathological anatomy museum.

Macabre museum devoted to historical Viennese murders.

The beautiful baroque library of the Hapsburg empire.