Ever since I came to Buenos Aires I loved the handy Guía T. It is basically your tiny bible to getting around BsAs by bus. Buses in BsAs are great – there are over a hundred different lines that will take you basically anywhere you need to go in the city (and for dirt cheap, but that is another story.) To know how to get from point to point, the Guía T is indispensable. Someone else has explained it better than I can so I will quote here from Wander Argentina:
There are three sections in the Guía T. In the front of the book, there is an alphabetical index of all the streets in Buenos Aires subdivided with various address ranges, each pointing you to a page with the appropriate map. The body of the Guía T is made up of tiny maps of the entire city with a list of the corresponding buses on the opposite page. In the back of the book are all the various buses listed in numerical order with the details of their routes and pictures of the buses to demonstrate the color scheme of each line.
Of course, many people have smartphones now, and you can use websites such as Viaja Facil or OmniLíneas to plot your trip. However, the little Guía T is still great – it requires no connectivity and is also super useful as a map when exploring the city.