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

The United States Capitol's former columns still stand.

Largest Roman Catholic church in North America.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

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

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

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

The site of the climactic scene from the classic horror film is now a historic landmark.

Home to items never before seen by the public.

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.