Cities are at the heart of Europe. As four of every five European citizens live in urban areas, their quality of life and the quality of their environment depends upon how cities look and how they function. Cities are also places where business is done, investments are made and jobs are created....

We study how the city system is affected by the possibility for the members of the same cultural diaspora to interact across different cities. In so doing, we propose a simple two- city model with two mobile cultural groups. A localized externality fosters the productivity of individuals when...