I've never seen anyone reverse MORE than a block in the wrong directon....
Re. CrimsonCyclist's comments on the hazards of Huntington Ave: excellent description! I would also include high curbs, interestingly angled train tracks, taxis (around the hotels), and crowds of oblivious arts patrons (outside the MFA, Symphony Hall, and the Huntington Theater). Mass Ave can be fun; Huntington is a royal pain. Tried Columbus Ave? It's wider & in better shape. Of course it also has those amazing cars legally parked on the center line (!)