The theme “borders and cities” has imposed itself in the latest evolutions of the European « refugee crisis ». Many debates and emergency initiatives emerged in Europe after events such as the shipwrecks of three boats full of migrants that caused a thousand causalities in the Mediterranean Sea in April 2015 or the German decision in August-September 2015 to welcome refugees from Middle-East—which was followed by large European debates on how to distribute the burden of refugees and whether to open or to close the borders. The question of asylum became the main focus of public debate not only at national level but also in cities, in human rights defense organizations and even at an individual level. In many different European countries, a public hospitality has been promoted and institutionalized, while more or less organized or individualized social forms of hospitality —conceived as charity or a sort of cosmopolitan solidarity— have been made public. At the same time, the same representatives of the State —or others— the media or even some citizens have been advocating rejecting and sidelining, or even encamping migrants and refugees. This situation, a true political moment that has given rise place to a widespread debate in Europe on both the status of migrants in European nations and the question of external and internal borders within Europe, has revealed the ambiguities, overlaps, contradictions and conflicts between the different methods of hospitality and sidelining. This is the context of the BABELS project, which by combining multi-sited ethnography with public anthropology, sets out a solid empirical and theoretical base to its intervention in the public debate on the place of migrants in public policies and social practices (“what cities do to migrants”) as well as on the signification and effects of the migrant presence (“what migrants do to cities”). The key concept in our thinking and fieldwork is the notion of “borders”. This project of public anthropology, based on the production of knowledge from and for society, consists of taking up the questions raised in Europe and the Mediterranean Region about the migrants, refugees and borders to reformulate them into theoretical questions and empirical issues. The project will be based on both knowledge already acquired and theorized by one group of members of the program and on new research questions that will introduce new elements of comprehension into the public debate. The three key questions — cities as borders, refuge or crossroads — incorporate thirteen local, individual or collective research operations. The BABELS project seeks to provide answers to a broad public as well as to institutional stakeholders, using knowledge from comparative ethnographies and working closely with concerned organizations, institutions and media. These answers revolve around the following propositions: - Contextualize the categories (such as migrants, refugees, illegals, strangers, etc.) produced by institutions or media and explain their underlying conception and deployment. - Describe and explain contemporary border situations (geographical, social, cultural) and their evolutions. - Enlarge the scale of public debates by “de-nationalizing” them, thanks to a research linking North to South by working on migrants’ paths as well as on public hospitable or hostile policies. - Demonstrate the fundamental link between cities and borders — major capitals or border towns — and help renew ways of conceiving public policies towards zones with a dense presence of migrants; with an eye to guiding political choices.