I agree that south of the autopista is not advisable. It's in the southern part of San Telmo and can be spooky late at night. You would be right next to La Boca and not far from Constitution and thoughs areas are to be avoided at night. I wouldn't recommend that area to anyone. I don't feel safe at night in that area at all. If possible, try to stay in Palermo, Almagro or Recoleta. Be very careful when using your cell phone anywhere in public in Buenos Aires. I read somewhere that there are approx. 4000 cell phones stolen each day here.