A wide and radical cultural, social, political, and economic transformation – defined by globalization – is changing the urban scene in the European cities. The migratory flows – conditioned from the world geopolitical scene and the territorial context of acceptance – and the complexity of the relational system of the post-modern city are the new items of the town and country planning discipline. The fundamental issue is to favor integration and the interaction between various cultures by a bottom up approach. Reflecting on the perception of the phenomenon of immigration and on the various forms of conflict or socialization of the multi-ethnic urban co-existence, we try to identify the socializing role of the public places. In particular, our attempt is to define the components of a new dialogue architecture oriented to promote the encounter between social, ethnic, cultural, of gender, … diversities. To such scope the attention has been focused on the configuration and the accessibility of the public spaces. This multi-cultural approach offers to the planning disciplines a new point of view to face the crisis of identity in the historical cities and the a-topia in the urban periphery. This is the first step to diffuse a spatial democracy: equity in the accessibility to goods and services, independently from the residence places and from the our origin or culture. It is important to remind that: “ … di una città tu non ammiri le sette o le settantasette meraviglie, ma la risposta che dà alla tua domanda …” (Italo Calvino, Le città invisibili)