Maracana stadium "was opened in 1950 to host the FIFA World Cup", at which time it was the largest stadium in the world. I have heard the stadium referred to as "the spiritual home of Brazilian football" a few times, and this year it will once again host the World Cup Final. Why is Brazil's top stadium in Rio, rather than in São Paulo, when the latter is a far larger city (not that Rio is small)?
In 1950 - when the stadium was built - Rio de Janeiro was the Brazilian capital city. That explain why the stadium was not built in Sao Paulo