This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

This monument owes its name to a quote by the famous civil rights activist and journalist.

This unauthorized stone mermaid was secretly carved out of public stone before being permanently preserved.

An actual 1957 Cadillac De Ville, encased in 15 cubic yards of concrete.

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

This statue of the "father of television" stands prominently in the United States Capitol.

This alley in downtown Chicago held the bodies of over 600 people after the fateful Iroquois Theatre fire.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

This unique historical monument features large concrete spheres designed to resemble fallen stars.

She stares out across six lanes of traffic, clutching a musket and infant with determination.

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

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

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

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

The first memorial dedicated solely to the Black troops who fought for the Union.

Washington D.C.'s most famous pianist, composer, and bandleader still tickles the ivories outside Howard Theater.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

Recorded as the first person buried in Arlington Cemetery.

Though his role as the inventor of baseball may be up for debate, fans still festoon Doubleday's grave with baseballs.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.