How to build up without a community? There is always a community. In this case we were the community. The new generations people at Fabbrica del Vapore in Milan. We were meeting for a 3 days encounter of european young architects. More than 150 architects that were sharing their methods, their projects, their knowledge and procedures. We built a citizen infrastructure for new ephemeral communities that could use it any time. The system we organized is a way to find different positions to manage the public space. The infrastructure allows to make a multiple fire to use public space in winter time and at night. A place to be together or to be alone in different groups. More than a center. A multiple center structure to be reorganized anytime. We use 80 wood boards from a built work excess. If we can built this infrastructure in three days, what can we built together with more time, communities and resources?