Buy a ticket and join the crowds at a game at Ibirapuera Gymnasium. If there's nothing on while you're in the area, you might like to check if they give a guided tour of the grounds.
This Moema sporting facility is an ideal place to begin your day of sightseeing. There's loads to explore in the area, like Paulista Museum, Municipal Theatre of São Paulo, and Ibirapuera Park. Wander around at your leisure at Ibirapuera Gymnasium before making tracks to these other fine attractions.
