I found the tourist Info office along the waterfront although I had to wait for some minutes to open (they go slowly… ). There was an English speaking woman that provided me with a simple but useful map and pointed me the basic sights. I made some questions about a place or two and she told me what buses to take and how to return back. There were also some leaflets about boats that go to the islands and things like that.
address:Avenida Belgrano and Buenos Aires
Alternative go to Galeria Rosario (San Martin 862 and Sarmiento 859) or at the terminal de Omnibus Mariano Moreno, Santa Fe y Cafferata. Address:Avenida Belgrano and Buenos Aires