Barrio de San Telmo is very nice on Sundays. There are indoor flea markets and at Plaza Dorrego you can find an antique market.
If you love to dance the tango, or love to watch it, you should visit ‘Festival de Tango’. Especially the ‘open classes’ for beginners are quite popular.
The shows where tango is mixed with other dance and music styles is extraordinary.
There’s also a tour to learn more about the history of tango. Which is very interesting.