Directly in front of the Smithsonian Castle is this statue of Joseph Henry. I mistakenly assumed it was James Smithson, but like I said, that was a mistake. Henry was the first Secretary of The Smithsonian Institution.
Trust me when I say that there are lots and lots of statues of people in Washington, DC, that you probably haven't heard of. I tried to make it a point to read the names on the statues to make sure I knew who I was shooting. Between that and Wikipedia, I hope I get all the names correct when I post pictures.
That building on the far side of The Mall is another branch of The Smithsonian, The National Museum of Natural History.