The holes in this wall provide a glimpse into Jewish life in Budapest, both past and present.

This sculpture honors the man who was known as the "Righteous Among the Nations."

The metal leaves on this tree are engraved with the names of Holocaust victims.

An abandoned cable car station located on the Danube stands like a haunted house above the river.

The world's oldest known salt mine.

An Austrian house of bones filled with hundreds of intricately painted skulls.

This skeleton-filled altar piece served as a backdrop to one of the most iconic scenes in "The Sound of Music."

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

Double spiral staircases are not unheard of, but they are very rare.

Austria's ultra-modern art museum looks like Cthulhu's giant alien heart.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.

This small, easily-overlooked sculpture recalls the first time Graz saw a live elephant.

The world's largest historic armory was established by independent citizens to defend themselves from the wars of larger forces.

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

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

Handsomely crafted representations of our round planet.

Museum devoted to the artificial language of Esperanto.

These two 15th-century metal rods allowed people to check if they were swindled or not.

This museum is dedicated to the little known ancient Roman history of Vienna.

A mechanical clock built in 1914, with a rotation of 12 historical figures on its face.

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

One of the most notable figures in the Wurstelprater’s history is often assumed to be a fictional character.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.