Cicerones is a non-profit that matches proud Porteños with visitors to go on 4-hour custom walking tours. You fill in a form outlining the kinds of things you are interested in (art, architecture, sports, etc), the area(s) of BA you are keen to see and they match you with a volunteer. I had a great time with my Cicerone, Ariel. He picked me up and we took the subte down to San Telmo and then continued on to La Boca and took the bus back up to Barrio Norte. Because the guides are volunteers they are not professionally trained, they are sharing ´´their´´ Buenos Aires with you. It is free, but the visitor is responsible for covering costs (transportation costs, any entrance fees and in my case, beer).