I am a first year student in the Urbanism Master track. I chose this particular path because I was interested in closely working with people, and how they use public spaces. Aside from creating socially sustainable places, there are other aspects as well. Spaces are always in the middle of existing systems (e.g. economic, social, ecological).
However, considering the ideas of urbanism from the twentieth century, there are many locations where opportunities to connect with these ecological systems were ignored, or went unnoticed. I think sustainability in urbanism is often about connecting these spaces to their surrounding systems, thus creating an integrated, sustainable design.