One of the features of São Paulo that would interest you the most is that its streets are all covered in graffiti; Underpasses, roads, streets, even buildings.
There is one more thing on top of the graffiti in this city: scribbles on buildings that look like coded cryptic writings. They are called ‘pichação.’ They are not colourful paintings like graffiti and many people do not think they add an aesthetic value to the city, nor they are adored by the city’s inhabitants. Actually they are not legal; while painting graffiti is encouraged, writing these is punishable by law. When you think somebody gets up at night when everyone else is sleeping and writes them on the hard-to-reach parts of buildings, you imagine that the city turns into a different theatre stage at night; these inscriptions are sometimes a political message, sometimes a bad word, and sometimes a declaration of love.
It seems that if the daytime has a language of its own, so does night. Some of the graffitis are real art works. Here are some places where you can run into a huge wall painted by a graffiti artist: The Old Town (Centro) is quite rich in this sense, walk the Praça Ramos de Azevedo Square and surroundings. If you are heading to the business district Faria Lima check out the walls os the skyscrapers. The bohemian neighbourhood of Vila Madalena is itself known as a graffiti neighbourhood due to the famous Batman Alley where a pedestrian street sided by two walls are covered with graffitis.