Libraries are also a good way to tour a city. Get a transit card from a grocery store or a convenient store (also a lotto ticket because you never know). Start with the main branch, then on to the various neighborhood branches. It’s important to pick a section you are interested in beforehand. Fiction might be too overwhelming, so I’d go for the math or computer technology sections. Once you’ve done this in multiple…
I'd add for Brazil, a great alternative to the libraries are SESCs. SESCs are cultural centers, funded by a payroll tax proposed by big business in the 50s when they were afraid of Communist sympathies in population. The result are extremely well funded community centers with big arts budgets for free exhibitions, exercise facilities, primary care clinics, libraries, cafeterias with affordable food and lots of space for people to lounge around. In many neighborhoods, they're the epicenter of social life. They've been a terrific way to break out of the downtown Sao Paulo bubble.