Too much to see!
The Paris of South America has the good and the bad things of a big city, you can see a lot of culture there, many historical places, great places to eat and is also very dirty, can be dangerous and no great landscapes to see. If you like antiques you must go to San Telmo, and specially on sundays there is a big flea's market.
Insider Tip:- Go to the Florida street to change your money, ask several guys the price and choose the best price. You can check the dollar price looking for dollar blue in google. - If you're going to stay several days you should buy the SUBE card which allows you to take the subway and the buses in the city. There is an app to find the buses or subway stations to take from one place to another: BA Cómo llego. - You have excellent free walking tours of Recoleta and the city center offered by Demasiado Tours.