After colonial times Latin America has been characterized by informal urbanization processes and spontaneous appropriation of the territory without any regulation or structure (Alcaldía de Medellín, 2006). Nowadays, in the specific case of Colombia, the migration processes continue and the main cities are still receiving thousands of people motivated for the economic opportunities or forced by the internal armed conflict. In Colombia, more than 75% of the population is living in cities and from that percentage, between 20 and 30% of the urban population is living in informal and precarious settlements. Colombia and Brazil are the countries with the highest rates of inequality and the lowest rates of urban security in Latin America (Echeverri, 2011).
Medellín is the capital of the department of Antioquia, the second largest city in Colombia and is located in the Metropolitan Area of the Aburrá Valley, the second largest urban agglomeration in the country.