Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

Hydraulic systems in an ancient underground Iranian city.

Few people have ever heard of, let alone visited, one of Turkmenistan’s most impressive natural attractions.

Complete town of 5,000 living out at sea on the world's first offshore oil platform.

This gravesite in the Amazon Rainforest was left behind by a failed Third Reich expedition.

This East German military command bunker was ready for World War III.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

Gliwice Radio Tower, likely the tallest wooden structure in the world.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A legendary speakeasy bookstore returns from the brink.

This incredible stone temple is a monument to death, victory, and fantasy architecture.

This hilltop warren of monastic dwellings is the result of centuries worth of Mongol attacks.

This peaceful Sikh gurudwara serves around 50,000 free meals every day within its gilded walls.

On the Pakistan-India border the militaries perform an elaborate theater of aggression each and every night.

The world's largest human gathering is held at the confluence of three sacred rivers, one of which is mythical.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

The first declared National Monument in the United States.

One of America’s oldest and spookiest hotels, thanks to the residency of ghosts, dead presidents, and Alfred Hitchcock.

A pyramidal marker where the borders of Venezuela, Brazil, and Guyana meet on top of Mount Roraima.

This "floating island" plateau sits 7,671 feet above the forest floor.

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A huge, bustling local market in Panama City.