One of the few cold geysers in Europe, its eruptions are powered by carbon dioxide.

Launched by Napoleon's soldiers more than 200 years ago, a cannonball remains embedded in the tower wall.

This region of Slovakia boasts some of the most plentiful opal mines in the world.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

Inside the Šomoška National Nature Reserve exists a unique rock formation rarely seen in the world.

Arguably Belgrade's only example of pure Art Deco architecture.

Backwards hour and minute hands and a timing mechanism that fluctuates with the temperature led to this clock tower's local nickname.

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

This fresco inside a Serbian cave church has been a source of disagreement.

Stone age urban planning.

Housed in a 1912 architectural masterpiece, this outlet of the Golden Arches is a real beauty.

Religious perseverance and cultural coexistence manifest in an architectural gem that multiple wars couldn't topple.

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

For over 40 years, this quaint little house has teetered on a rock in the middle of a river.

A Serbian church lit by chandeliers made of weapons.

A sinuous path among steep cliffs creates a stunning sight in southwestern Serbia.

Legends of treasure and spirits flow from this this fairy tale-like oasis.

Structure built from the skulls of vanquished foes.

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

Just across from the "Last Supper" painting is the famous painter's vineyard, a gift received for creating the masterpiece.

Sip a Negroni Sbagliato in the bar that invented it.

A British Commonwealth cemetery in the heart of Milan, with 421 allied soldiers died during World War II.

Invented in the mid-19th century, this machine could send copied images via telegraph lines.

This small Milan street is filled with colorful homes and a rich history.