Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

Just a man taking his prehistoric pet for a stroll.

A walkable map of the world, made from soil and stone by one man.

A detached cement mixer has been transformed to resemble a relic from some obscure NASA mission to Oklahoma.

A trailblazing sovereign nation tucked in the American state of Wisconsin.

This quirky museum has a collection of more than 15,000 bobblehead dolls.

An off-the-beaten-path place to literally hang beneath Milwaukee's Holton Street Bridge.

A giant, Gilded Age mansion that once belonged to the beer baron of Milwaukee.

A giant ball made from pieces of an old Jeep.

This secluded walking trail is a hidden gem of a Pittsburgh park.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

Despite being stolen multiple times, this civic electrician's street corner Snoopy won't be stopped.

There aren't too many operational funiculars around, but Pittsburgh has two!

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

This permanent exhibition celebrates the finest of our heartless automatons both real and fictional.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

Where the U.S. government kept its actual treasure, before Fort Knox.

A celebrity from the late Cretaceous period.

Seemingly unremarkable items like empty sushi trays, chef hats, and freshness stickers are being preserved so future generations can look back on this beloved cultural import.

A super-sized promotional trick that is now a D.C. landmark.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.