Purchase a ticket and join the crowds at a game at Estadio Ricardo Saprissa Ayma. If there's nothing on while you're there, you might like to check if they offer a tour of the grounds.
You'll soon learn why this San Juan sporting facility is a hit with travelers. If you're searching for other things to see here, National Museum of Costa Rica, National Theater, and Museum of Costa Rican Art are in this area too. They won't take very long to get to from Estadio Ricardo Saprissa Ayma.