The European city would be nothing without the constant coming and going of its inhabitants, whether they be refugees, tourists, guest workers, expats, or digital nomads. This ebb and flow has a profound effect on how we perceive, administrate, and design our cities. Conceived by Crimson Historians & Urbanists, this publication brings together a number of European cities that are marked by migration. Based on essays by local scholars and experts, the investigation also includes a catalogue of 100 projects emerging from these cities that tackle the issue of migration in many different ways and on different scales, showing how planning and architectural design can play a crucial role.