Although ‘arrival infrastructure’ is central to the experience of migrants arriving in a new city, is it sufficient to form a ‘hospitable milieu’? Our article compares newcomers’ experiences with ‘arrival infrastructure’ in two European cities: Brussels and Geneva. Based on ethnographic research with 49 migrants who arrived a few months earlier, we show that arrival infrastructure is Janus-faced. On one hand, it welcomes newcomers and contributes to making the city hospitable. On the other hand, it rejects, deceives and disappoints them, forcing them to remain mobile—to go back home, go further afield, or just move around the city—in order to satisfy their needs and compose what we will call a ‘hospitable milieu.’ The arrival infrastructure’s inhospitality is fourfold: linked firstly to its limitations and shortcomings, secondly to the trials or tests newcomers have to overcome in order to benefit from the infrastructure, thirdly to the necessary forms of closure needed to protect those who have just arrived and fourthly to those organising and managing the infrastructure, with divergent conceptions of hospitality. By using the notion of milieu and by embedding infrastructure into the broader question of hospitality, we open up an empirical exploration of its ambiguous role in the uncertain trajectories of newcomers.