See the street view for: R. Catumbi - Vila Butantã Vila Butantã, São Paulo - State of São Paulo, Brazil.
To his left, a large police station.
To the right, dudes selling drugs on the entry of a small corridor street.
The drug sellers did keep the peace in their business area, and Ciro never got robbed, and would come back from university parties on foot late through the favela.
But Ciro's friends did say that things got much worse after Ciro left, for example a flash kidnapping was reported in 2015.
Wikipedia says that this favela started in the 60s and 70s as settlements of the builders of the University, and that many of the people there still work for the University.
This is consistent with the terribly old buildings Ciro saw when he was at university. They even had the building skills to build their own homes.
The state just has to either legalize those people, or give them houses somewhere else nearby. A world class University is the most important thing a poor country can have, and its image cannot be jeopardized like that.
The existence of that favela, right next to one of the most important universities in Latin America, puts Brazil's surreal social inequality into perspective.
The porters of the apartment block Ciro lived all lived in the favela. Yes, in poor countries lives are worth nothing, and some poorer people work by watching the entrance of buildings of less poor people 24/7 to guard it from other even more desperate poor people who might want to rob the not so poor inhabitants.
They were incredibly nice hard-working people, and Ciro spoke often with them. If only given the opportunity, those people could be amazing engineers or scientists obviously.