The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The house where John Wilkes Booth conspired with his co-conspirators.

Home to items never before seen by the public.

You might know it as the Overlook Hotel, but the inside is not going to be familiar.

Home of Howard Hughes' Spruce Goose.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

One of the world's tallest, oldest, and most disgusting chocolate cascades.

The seamy, underground secrets of Portland's criminal past.

The Bucyrus-Erie model 1850B electric shovel, or "Big Brutus," the largest existing electric shovel in the world.

Tribute to the famous Notre Dame football coach who died in a plane crash.

Marking the spot where a conquistador gave up his search for the fabled Seven Cities of Gold.

Metal sculpture folk art lining the Kansas Highway.

The United States's largest hand-dug well is topped with a state-of-the-art museum.