This is a public space rehabilitation project in the San Pablo Xalpa housing unit, Mexico City. By taking a placemaking approach, we transformed the alienated sectors of the housing complex into a community of BARRIOS—what we termed COMMON-UNITY. We worked around the physical barriers created by the residents in common areas to make them permeable, democratic and meaningful. Through participatory planning, our design strategy substituted dividing vertical structures for sheltering horizontal ones. We implemented roof-modules equipped for a diverse program (blackboards, climbing walls, handrails and nets). The new design spoke for itself: residents agreed to remove 90% of the barriers and the recovered public space became an extension of each apartment. The new space facilitated a different kind of ownership and appropriation: one that habituates inhabitants to work for the common good.