Mostly we walk because everything is within easy reach. Bull's Gym, where we work out twice a week, is exactly 500 paces from our apartment. Pretty much everything else necessary to sustain life -- from a world class hospital to grocery stores -- is closer. La Hormiguita, which does our laundry, is about 10 paces; the nearest fresh vegetable stand is maybe 20. Several news stands, Los Pinos and Los Molinas (two of our favorite restaurants), our banks, and a grand old-style movie theater with seating for several hundred, all are within a couple of blocks.
We got into the habit of hoofing it in Austin in January 2007 after we sold the last of the approximately 23 cars we had owned over the years. In BA, it's just easier to do without a vehicle. Plus walking and using public transportation both are great ways to soak up the architectural wonders of our new hometown. The photo above shows part of the murals at the Facultad de Medicina station, just one example of the 1930s tile work adorning many of the subte stops.