Go inside to really appreciate this 500-year-old technological masterpiece.

A tiny church on a man-made island in the Adriatic.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A curious little museum dedicated to the furry feline in the cat haven that is Old Town Kotor.

A monument on the pavement marks the spot where two cultures that shaped Sarajevo come together.

This picturesque monastery at the base of a cliff is a peaceful oasis open to all visitors.

A number of craters left by fatal mortar strikes have been filled with red resin to remember those lost during the Siege of Sarajevo.

Oriental bazaar in the heart of Sarajevo.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

Bridge that died in war and was resurected.

The oldest arboretum on the Dalmatian coast doubles as the gardens of Kings Landing in "Game of Thrones."

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

Longest fortress system anywhere in Europe.

A miniature train-ride through Slovenia's largest cave system.

Baroque celebration of the end of the Great Plague of Vienna.

Op-art architecture designed for happiness.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Hungarian Jews were ghettoized during the Second World War, but little remains of the original wall that closed the Jewish people off from the rest of the city.

The metal leaves on this tree are engraved with the names of Holocaust victims.

Budapest's Communist-era statues, banished to the suburbs.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

Gargantuan home of Russian science.