GSD 6445 explores opportunistic design strategies for informal settlements using the case study of Medellin. The study of the miraculous transformation of Medellin and the provision of infrastructure will be the departure point for remedial and anticipatory strategies for the over 250,000 informal settlers who precariously live in the steep hillsides of the Aburra Valley. Topics of erosion, geological risk, water management and food production will be prevalent in the unstable slopes of the metropolis where more land invasions will be expected in the coming 40 years. The class will build up on research that was started between the Social Agency Lab of the GSD and the urbam thinktank of EAFIT, led by the former director of Medellin’s Urban redevelopment Agency, Alejandro Echeverri. Alejandro will be involved in the class and its findings will be summarized in a report.