An imposing Omani fortress surrounded by date palm trees.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

The monumental home of Prussia’s eccentric "Cannon King."

Rising out of miles of farmland, these buttes are sometimes called the world's smallest mountain range.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

What happens when you cross a mayor and a painter?

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

A naturally beautiful, seemingly bottomless deep blue spring.

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

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.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

The solemn exterior conceals an opulent interior of this 17th century church.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.

Legends surround an ancient tree trunk riddled with nails for good luck.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

The beautiful baroque library of the Hapsburg empire.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.