"Cap and Black Widow are are very different people. It’s kind of like this odd pairing. She has very questionable morality, and she makes a living, lying. Cap couldn’t do it, if he tried." - Chris Evans
Protip: This is a really bad question to ask when visiting the National Mall. We have 8 buildings surrounding the Mall, and a total of 19 museums, 9 research centers and the National Zoo. A S.H.I.E.L.D agent should know better!