Two stunning 17th-century libraries and a cabinet of curiosities.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

A surreal statue honoring Prague's favorite literary son.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

Breathtaking and huge 430 year old maps of Italy.

Real bones which are said to have belonged to a Polish dragon.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This endearingly discomfited urinating statue commemorates the sneaky pees had by us all.

An abstract monument to a symphonic composer.

A subterranean house of worship carved right out of the bedrock.

A former imperial sea-fortress and Soviet prison.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

Venice's island of the dead.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

The massive white mound and accompanying water terraces are a striking geological oddity.

This quaint Hungarian railway system is operated exclusively by children between the ages of 10 and 14.

Legions of Roman soldiers bathed in this ancient spa complex under a Budapest transit station.

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

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

A 19th-century artistocrat's mansion, turned into a library, hidden in a modern library.