Buy tickets and join the crowds at a game at Cesar Correia Stadium. If there's nothing happening while you're in the area, you might like to check if the stadium offers a tour of the grounds.
You'll soon find out why this Campo Maior sporting facility is popular with travelers. If you're looking for other things to see here, Albufeira da Barragem do Caia, Casa Museu de Santa Beatriz da Silva, and Lagar Museu do Palacio Visconde d' Oliva are in this area as well. They won't take you long to get to from Cesar Correia Stadium.