A priceless collection of the Nation's cryptologic history.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

A former major munitions plant that has been converted into a sprawling art space.

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

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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

Largest Roman Catholic church in North America.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Giftshop catering to cryptozoologists and anyone with a sense of humor.

A nostalgic bibliographic gem.

The most accurate timepiece in the world.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

At 207 feet, one of the world's longest continuous escalators.

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.

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

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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.