We took a much-awaited (for Chris and I, anyway) tour of the Congreso - we'd been trying for months with something blocking us at every turn. In the Congress library, they have, by law, every book and newspaper published in Argentina. That makes for a lot of books.
Their, uh, Chamber of Representatives was pretty sweet, too. Fingerprint ID voting and a terrific stained glass window on the top of the building. Too bad you can't take pictures inside.