Military

An 11th-century mountaintop fortress that played a crucial role in Italy's papal wars is now a vacation rental.

The elliptical citadel resisted the advance of the mighty Ottomans several times, thanks to the military prowess of the "Dragon of Albania."

This abandoned oil depot produces world's longest echo in a manmade structure.

The only substantial part of Nazi Germany's formidable defensive line through Northern Italy that survives today, largely intact.

The obelisk honors the cyclist troops who were killed during World War I.

The contents of this safe survived a 37-kiloton nuclear bomb.

A tribute to the little-known group of women who were the first ever to fly aircraft in the U.S. military.

A 6th-century stone lies at the site of the mythical battle waged between King Arthur and his nemesis Mordred.

This quirky piece of naval artillery has been deafening Canadians for over a century.

An eclectic sculpture park rises atop a giant pile of ashes in Sweden.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

Vienna's underworld of tunnels and subterranean rivers made an iconic appearance in a 1949 Orson Welles film.

Canada’s surprisingly controversial monument to Dwight Eisenhower.

A preserved Nazi labor camp now has a Holocaust museum on site and memorials to the thousands that died while imprisoned at the camp.