Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

Every drop of D.C. tap water flows through this old waterworks.

A derelict bit of transportation infrastructure hidden in the woods.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

One of Ireland's most infamous prisons for rebels including men, women and children.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The modern birthplace of Irish freedom.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

What remains of the summer palace of King Kamehameha III.

This museum of Hawaiian and Polynesian culture is the legacy of the last descendant of the Kamehameha Dynasty.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

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

This public baseball field is a beloved remainder from of one of the most historic stadiums in the country.

These grassy undulations on a stretch of University of Michigan campus aren't bad landscaping, they're art.

The site of the climactic scene from the classic horror film is now a historic landmark.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

An ever-evolving wall of graffiti art off East Liberty Street.

A steam trawler with a whiskey-soaked history driven ashore in 1960 resides rusty but still standing on the shoreline.