For the most important living architect of the TerReForm to walk into the front door of a crowded bar on Capitol Hill would be to create all manner of unnecessary distractions. Doc would be recognized. People would want to demonstrate how important they were by walking up to him and introducing, or reintroducing, themselves. It would become tiresome and it would wear him out. People would talk about it, perhaps even to the point of fouling up whatever mission the Seven was being organized for. Of course Doc had used the back way.