Given the centre of BA can be quiet on a Sunday we caught the subte blue line to Independencia and then made the 10 minute walk down to San Telmo. It is very busy street market that sells everything from tacky imports through to fine antiques oh and fruit & veg if you need something to go with your dinner. In amongst all of this are magicians, tango dancers, music bands, mime artists and just about every conceivable type of life imaginable. A very long street which got very crowded but at all times it felt safe & fun. Lots of street food or restaurants to eat in - or just sit & watch the world go past. Look out for the antique jewelry shops - sheer amount of stock is glitteringly impressive. By chance we happened on Museo Penitenciario - 378 Humberto Primero - museopenitenciario.spf.gov.ar which couldn't find in Tripadvisor listings. Free and worth a look to see what was a working prison dating back to the 18th century looks like.