I was browsing the Streets of Washington Flickr page, a collection of historical photos and postcards, and found some cool ones of the Old Soldiers' Home, now called the Armed Forces Retirement Home just east of our area.
The photos show Scott Hall, now called the Sherman Building, the old main building. It was finished in 1857. Pretty neat! Here's more about the Soldiers Home.
The one with two photos is from a stereopticon, a kind of 3D imaging tool like a Viewfinder.
And here it is in 2012, from Google Maps