update
Okay, so I'm a little bit stupid. It's not the Statehouse next to us, it's City Hall. I went for a walk with Bella this afternoon, and happened to notice some yellow paper signs taped to telephone poles that said "SET" with an arrow. So... I followed them. About seven blocks away, there were a whole bunch of large trucks and an obvious film production of some sort. Sadly, it was not "The Brotherhood," but a film called "27 Dresses" (http://www.imdb.com/title/tt0988595/). They've moved this way and are now filming a scene on the street between City Hall and our hotel, Bella and I were watching while we ate dinner. I got directions to "the Hill" so maybe we'll wander up there tomorrow. But! I am about 98% certain I got a glimpse of Jason driving by. After my walk (which I nearly got lost on) I was moving towards the crosswalk, as the hotel was on the other side of the street. A silver BMW paused at the corner, then turned right, about ten feet away from me. I'm so sure it was Jason Isaacs driving, it looked just like him, but he was talking on a cell phone so I'll never be 100% sure. But I like to believe it, so it's true!