Synagogue built from the stones of Solomon's temple contains the golem of Prague.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

The first museum in the world devoted to sexual gadgetry.

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

Macabre astrological automaton clock dating to the late 1400s.

This lurid German fountain plots the sad course of marriage from dating to death.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

A winding district gerrymandered into the shape of a mantis.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Mountain where Jesus was first tempted by the Devil.

A beautiful but toxic fountain of mercury.

This ghost town was once a cult-like religious utopian settlement.

Home to the deepest rift anywhere on Earth.

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.

Paranormal activity on the great lakes.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

The scene of one of the darkest moments in American labor history has been left essentially untouched since the tragedy.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.