Urban Tactics for Informal Cities

I was looking through some old work and lectures from my undergrad to help me figure out my potential thesis idea, this is pieces of a lecture by Professor Cowherd in my History of Architecture that really caught my interest then, and now.  

favela Soa Paolo - dynamic between the city and the informal city

small scale change

Medellin intervention - urban scale - 

Tactic: using the areas that remind people of the worst because of what happened there and putting public facilities (library, bridges etc) 

one of the architectural interventions - using design to create change