This historic black and white monastery is one of Bulgaria's architectural jewels.

Walk or bike along a narrow strip of Belgium sandwiched by German territory.

A little sculpture with a large wardrobe.

Cozy basement bar sports an inventory of over 2,000 beers.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

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

Physicist’s epitaph provides final confirmation to a career of turmoil.

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

The world's oldest known salt mine.

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

Museum devoted to the artificial language of Esperanto.

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

Handsomely crafted representations of our round planet.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

A giant interactive periodic table with real samples of the elements.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

Macabre astrological automaton clock dating to the late 1400s.

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

The bombed out remains of the old church were kept intact next to the new one, as a reminder of the futility of war.

One of these two land speed record-breaking vehicles went so fast it shattered the sound barrier.