Fascinating museum dedicated to the under-appreciated medical history of urology features some wince-inducing devices.

This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

A celebrity from the late Cretaceous period.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The most decorated dog of World War I is preserved in the Smithsonian.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

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

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A wondrous old library overlooking the nation's capital.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

Home to items never before seen by the public.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

The ruins of an abbey believed to have been founded by Charlemagne in the 9th century.