I did a post on my top 5 things to see in Rio de Janeiro, here are my top 5 things to see in Buenos Aires.
1. La Boca (the most interesting part of BA)
2. Plaza de Mayo
3. Evita Peron's grave in Recoleta Cemetery
4. Japanese Gardens
If you are in BA on a Sunday this is a must!
If you are vegetarian or vegan check out Picnic in central BA. Food is delicious, there is a great variety of juices and I had vegan tiramisu which was amazing.