The Hipodromo Argentino de Palermo is the horse racing tracks in Buenos Aires. It's in Palermo (as the name suggests) a stone's throw from the 3 de Febrero parks.
The Hipódromo de Palermo holds horse races every Saturday evening until 9.30pm.
Access to the Paddock stand, at the corner of the avenues Libertador and Dorrego, is free, and watching both the races, and the people betting, is a unique experience.