"See

If you are a fan of walking in open green spaces and parks in big cities like Buenos Aires, be sure not to miss a promenade in Palermo, a beautiful area in the eastern part of the city. Here you will not only find open spaces to walk in, but a large lake where you can rent paddle boats and an immense flower garden with free entry!
Another great place to walk along and experience Argentine street life in a safe area (during the day only, folks - interesting characters emerge here at night!) is El Puerto de Buenos Aires.
The National Immigration Museum is not open on the weekends like Moon Guidebooks says. Use the Retiro subte.
La Boca has the Caminito pedestrian street with arts and crafts. There is also a river cruise you can take from there. There is a huge metal structure across the river which is picturesque. Tango dancers are in the cobblestone streets. You may try to catch a rowboat to Avellaneda on the other side of the water for 0.50 pesos (0.125 euros), but the rower may not allow you to if you are a tourist, citing it's dangerous (peligroso). There is no subte to La Boca, but many buses go there. In addition to tango, La Boca is famous for its football, and you may also take a tour of the La Bombonera Stadium. The buildings are painted in bright colors. You can also take pictures with you and a tango dancer for a small price! But if you want a true tango experience that is not put on a sliver platter for a European or American tourist, read below and experience the true Buenos Aires Tango experience.
The prices for most everything in La Boca is 2 to 3 times what it is in the rest of the city. It's been over tourist-ified, but is enjoyable if you just feel like being a tourist. Don't even think about coming here at night. It's safe during daytime in the Caminito neighborhood.
The Cementerio de la Recoleta: This is where all the rich families in Buenos Aires have their final resting places, usually in above the ground tombs. Check out the calico cats who have haunted the cemetary for generations. Be sure to visit the tomb of Eva Perón, the bastard daughter of an aristocrat who, despite having the most visited tomb in the cemetery, is considered by many to be too "low class" for eternal interment in Recoleta.
The Palermo Viejo district: This is a trendy neighborhood with charming cobblestone streets, bookstores, bars and boutiques; definitely better than the touristic San Telmo area for a nightime excursion. The Plaza Italia station is the closest metro stop.
More information is available at the Buenos Aires official tourism website, including suggested itineraries."