The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

Deep scars on the earth left by the Ice Age.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

This abandoned bridge to nowhere stands secluded in the woods of a Cleveland suburb.

Take a drunken tour inside the world's largest known geode.

The train collection of an eccentric New England seafood mogul is now a National Historical Site.

The pop art icon's gravesite is broadcast 24 hours a day on his museum's website.

Featuring a Loretta Lynn display and a re-created coal mine exhibit.

At this rural museum, visitors can experience "Boomtown U.S.A.," a lifelike re-creation of an oil boomtown in the 1930s.

Named for a prominent scout and explorer, this Wyoming state park encompasses a replica of an 1840s trading post, a 19th-century Army outpost, and early 20th-century automobile lodgings.

These dramatic cola-colored falls have appeared in a poem by Henry Wadsworth Longfellow and a song by Sufjan Stevens.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

This abandoned, windowless concrete block is one of the strangest buildings in Tulsa.

What was once a summer home next to a waterfall has now become littered with graffiti and children in swimsuits.

Yup, that's where the name came from.

This lighthouse has been guiding shipping into the Golden Gate since before the American Civil War.

Once one of the most polluted caves in America, now an environmental success story and a museum dedicated to caves.

Nature (and graffiti) reclaim this old waterworks that has been surrounded by a bike path and network of walking trails.

This magnificent natural sandstone bridge is one of the largest in the world and is an iconic symbol for Lake Powell.

A collection of huge Pre-Colombian structures in Alabama.

A preserved trolley track that was transformed into a museum of transportation.

Historic seaside park featuring explorable, abandoned military structures.

A 100-foot metal tower and swinging bridge that provides stunning views of mountains in five states.

An assortment of armored tanks and Howitzer cannons in the middle of the Sonoran Desert.