Buenos Aires is a great walking city. No matter where you start out, you'll find beautiful architecture and tree-lined streets as you explore various areas. If you get lost, friendly Porteños will help you out along the way, as well as offer advice on their favorite things to check out. I've figured out a few itineraries for you here, but I'm sure you'll find plenty of your own along the way.
More Do-It-Yourself Excursions -- The Buenos Aires City Tourism kiosks scattered throughout the city have maps that can be used for self-guided tours. The Golden Map, available at almost all hotels, also has some self-guided walks for various neighborhoods in the city. One pamphlet that the city provides contains information about a special cellphone tour, where participants punch in codes at various destinations and hear explanations in English, Spanish, and other languages, including recordings of historical events at the various locations. Ask for this specific brochure, but know that the phone system does not always work well. Other themed tours include "Women of Buenos Aires" or focus on such important historical figures as Evita, Lorca, Borges, or Gardel, with addresses and descriptions of the places you will see. Some of these tours cover large distances not suitable for being covered solely by walking.