A museum about a language doesn't exactly sound titillating, but this fascinating gallery inside the reformed Estação da Luz train station in Centro features a wealth of interesting permanent exhibits documenting the Portuguese language and its rise as a separate but equal tongue to that of European Portuguese. Almost everyone who visits walks out not only more educated as to why Brazilians speak the way they do, but a little bit surprised about how well done the whole museum actually is. It's not as high-profile as more famous spaces like MASP or Pinocoteca do Estado, but well-worth a few hours of your time.