An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

This beautiful medieval Serbian monastery is home to frescoes, peculiar sculptures, and historical curiosities.

The unusual sculptures are believed to be powerful political symbols.

An 11th-century Byzantine church with medieval Serbian history and spectacular views.

Once a beautiful palace, this structure is now known as the ''museum of destruction."

This medieval monastery represents an architectural blend of eastern and western European culture.

This 15th-century Serbian Orthodox monastery also contained a school for illuminating manuscripts.

The interior of this Serbian royal family's mausoleum is covered with exquisite mosaics.

A Serbian church lit by chandeliers made of weapons.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

A medieval gate once used as a prison and how home to a city museum.

In a divided Germany, Potsdam's "central" train station was relocated to the city's southern suburbs to avoid West Berlin.

A poignant mural honors the heroic teenage non-conformists who took on the Nazis and paid the ultimate price.

The largest mosque in Germany.

The site where a plot to assassinate Hitler was planned—and its conspirators were executed—is now a powerful memorial to the German resistance during World War II.

A historic casino where Dostoyevsky is said to have lost it all on a single spin of the roulette wheel.

This ornate Weser Renaissance house was also the home of an infamous witch hunter.

The original burial place of this preeminent 18th-century Jewish philosopher was razed by the Nazis.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

A statue of Vladimir Illyich Lenin guards this abandoned building in the "Forbidden City."

The world's first and only three-segment bascule bridge folds up into the shape of a capital "N" to let boat traffic through.

A two-inch thick solid brass rod that extends an astounding one kilometer straight into the earth.