Countless grotesque faces stare out from this eerie Prague art wall.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

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

The first museum in the world devoted to sexual gadgetry.

Macabre astrological automaton clock dating to the late 1400s.

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

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

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

Modern art commemorates one of the first military actions of World War II.

This antique thermometer honors the creator of the first universal temperature scale.

A huge wooden clock that is so beautiful its creator was forcibly blinded.

The oldest housing complex in Riga is a mini timeline of architectural trends.

The Guardian of Tallinn.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

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

A former imperial sea-fortress and Soviet prison.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

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

The beautiful, ornate weather station is the most popular geocache in Salzburg.

Ugly 18th-century dwarf statues living in a perfectly landscaped Austrian garden.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

Art and armour fill every inch of this rich kid's Italian villa.

An incredible menagerie of more than 3 million taxidermied animals at the oldest science museum in Europe.