The remains of this medieval Roman road and lookout towers dot the rugged coastline of southern Lazio.

A fiery crater has been burning in the Karakum Desert since 1971.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

The remote outlaw hideout of Jesse James, Butch Cassidy, and the Sundance Kid.

The peaceful gravesite of a rugged wild west gunman echoes the touching story of his last days.

Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

A monument to the military service of America's greatest traitor refuses to even name him.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

You must take the A train... to the last active cemetery in Manhattan.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

Local lore holds that Butch Cassidy took an escape route through Red Canyon's sandstone hoodoos after an attempted murder.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

Gorgeous views of Italian mountains and valleys form the backdrop of this unique open-air theater.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

This 3,800-year-old site contains markers used to study the movement of the sun and moon and create a lunar calendar.

The granddaddy of English geoglyphs dates back to the late Bronze Age.

An artsy hidden staircase leads to breathtaking views of San Francisco.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.