America's post-nuclear-attack chambers of Congress.

The site of Paul Revere's historic two lantern warning.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

A massive sea stack famous for its appearance in The Goonies.

The land is home to swimming ponies and a legendary 18th-century treasure.

A motel dedicated to Southwestern nostalgia.

The highest point in Washington state is a volcano covered in glaciers.

This "second" cemetery represents New Orleans' attempt to keep cholera at bay.

100-year-old shipwreck you can walk up to at low tide.

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

Treehouse motel and treehouse-building school.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

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

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

This historic "City of the Dead" lies prominently in the center of New Orleans' famous Garden District.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

The magic's in the hole!

Possibly the most beautiful carillon in the world, set atop Iron Mountain in Florida.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.