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

An artist's cute bronze subway sculptures belie his violent artistic past.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

Strange red rock formations that have been attributed to a higher power for hundreds of years.

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

A tiny piece of the Moon is embedded in this stained glass masterpiece.

Largest Roman Catholic church in North America.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

The world's longest known cave system.

The United States Capitol's former columns still stand.

Elevated freight railway turned wildly successful urban park.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Famously misunderstood wonder of the ancient world

A showcase of canine neckwear spanning five centuries of doggie fashion and function.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.