Separated across several small floors in the beautiful Estação da Luz this museum was a pleasant…read moresurprise. On the first floor you'll find poems, graffiti, and political slogans that may go over your head if you are not familiar with Portuguese (or another Romance language). Going up again takes you to the biggest floor which expounds on the origins and influences of modern Brasilian Portuguese along with some light insights into the history of Brasil. It's on the smaller side but if you read every poster you could spend more than an hour without even watching their video presentation (included in the ticket price).
Cheap and easily accessible, but only worth it if you're into words.