Built by the patriotic residents of Boonsboro in a single day.

Bizarre Cavern.

An 1830s street scene and roadside relics trace the country’s first great highway

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

An astounding collection of medical specimens, including bits of President Lincoln.

An old pay phone rewired to play local bird calls and songs at the press of a button.

The headquarters of the Audubon Naturalist Society is a small slice of heaven for nature lovers.

This suburban house is made of dirt, and almost sparked a revolution in home construction.

A merry-go-round that became a rallying point for the early Civil Rights Movement.

Centuries of crashing waves carved out this small hole in the rock, which lights up at certain parts of the year.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

This square in downtown Eugene is dedicated to the novelist and countercultural figure Ken Kesey.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

Once a slice of Cold War-era military history, this museum is finding its future in the stars.

Haunted dolls, macabre artifacts, and more make up the collection of the “most haunted museum in the world.”

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

Believe it or not, the now-ubiquitous California avocado originated in Guatemala.

The world's tallest aluminum statue is also the world's tallest image of a winged Virgin Mary.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

Home to items never before seen by the public.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.