This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

This WWII-era military installation once held an entire city within its walls - now, its walls are falling down.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

Colorful boxes placed over the dead are left to rot and crumble.

This whimsical stacked cabin looks like something out of a children's book.

The king of U.S. high points towers over every other peak on the continent.

A trading post in the North Pole where children send letters.

Four-story concrete hotel never opened to customers.

A morbid gateway to an Alaska town prides itself on the hunting history it represents.

This mile marker stands at the unofficial end of a highway built to defend the United States from a Japanese invasion during World War II.

One woman's dream became a train hotel in her backyard.

Berkeley Springs State Park boasts the nation's only monument commemorating presidential bathing.

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

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

A 315-foot spire jutting out from the Blue Ridge Mountains makes for breathtaking views.

A Nessie-like monster supposedly lurks in this lake.

Thomas Jefferson's estate is home to hundreds of varieties of historic fruits and vegetables.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

A nourishing complex of found object art, paintings, and sculptures that celebrate key figures in Black history.

A wonderful display of arts and crafts handmade by local artisans in the Southern Appalachians.

The U.S. Supreme Court's secret Cold War relocation facility in the mountains of North Carolina.

The Midwestern United States' tribute to Michelangelo is a foam statue sprayed with gaudy gold paint.

Marine fossils from the Devonian period are exposed at this park.

The oldest operating Mississippi River–style steamboat still navigates the Ohio River.