At 207 feet, one of the world's longest continuous escalators.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

God's Saharan sandbox of wrath.

This huge pile of volcanic boulders hides a stunning network of secret grottoes.

A marvel of Byzantine engineering under the streets of Istanbul.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

This famous city eluded concrete detection until the early 2000's.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

The ancient latrines of the Greeks, in all their public glory.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

Roman ruins top white travertine terraces formed by ancient hot springs.

Visit the monolithic tomb of America's most famous general.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The highest bridge in America was built for an almost unnervingly small amount of money.

When ecosystems collide in the arid Southwest.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

Berry Gordy Jr.'s old home was the original headquarters of Motown Record Corporation.

The 80-foot tire that looms over Michigan's I-94 was once a Ferris wheel in the New York World Fair.

The first declared National Monument in the United States.