we did a 3 hour tour of the Central sites of Buenos Aires, and our guide was knowledgable and funny. He even gave details on the economic problems of 2000 and how they are just coming out of this. We hit briefly all the top 25 or so, give or take a few, sites plus a few extras like the Mothers of the Plaza de Mayo march on thursday. if it is your first time and first day in BA, do this first for orientation. $28 US for us 7-9-07.