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

A remarkable time capsule of American manufacturing deep in Maryland coal country.

This 19th century train workshop is a treasure trove of railroad history.

Several times a year, during low tide, two pairs of historic train tracks are revealed on this New Jersey beach.

Its buzzing collection honors vibrator history.

An abandoned bus station transformed into a museum dedicated to the history of Greyhound Lines, in the place where it all began.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

An Industrial Revolution-era public work that purified water using nothing but sand.

A Seussian sculpture made of brass instruments.

A former barn converted into a massive train diorama.

More than a century of radio history is told in these displays.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

Two hundred tons of pioneer artifacts were painstakingly recovered from a shipwreck at the bottom of the Missouri River.

A little piece of the Shire is hidden behind a plant nursery in Port Orchard, Washington.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

To honor his gardening wife, this yard artist turns bowling balls into playful, colorful sculptures.

Hundreds of hopeful gold miners came here to get rich, but only two years later the small town was deserted.

Hamburgers are intensely proud of their tunnel beneath the river.

A poignant memorial to a young boy whose death spurred a dramatic increase in organ donations in Italy—dubbed the "Nicholas Effect."

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

A century-old network of freight tunnels underneath the city's historic business district.

This large midwestern cavern features impressive rock formations and an underground waterfall.