When you arrive in Buenos Aires, finding information about the milongas, classes, etc. is absolutely vital. There is one source that contains everything you need to know, and it is available for only $2 at the kioskos where newspapers and magazines are sold. Guia Trimestre B. A. Tango (September/October/November) is invaluable. The guide contains listings for classes and practicas by day, dance salons, and everything else related to tango that you can imagine, including telephone numbers for teachers and milongas so you can call to verify the location, time and day. It is printed in a small format, convenient to carry with you during your stay. Be sure to buy a copy when you arrive in Buenos Aires.
Pichi
