This paper argues that existing models of urban concentrations are incomplete without considering the fundamental aspect of proximity: face-to-face (F2F) contact. F2F contact has four main features: it is an efficient communication technology, helps solve incentive problems, facilitates socialization and learning, and provides psychological motivation. The authors develop formal economic models to illustrate these features and their implications for urban economics. They emphasize that F2F contact is particularly important in environments where information is imperfect, rapidly changing, and not easily codified, which are key characteristics of many creative activities. The paper contributes to the understanding of F2F contact by showing its unique behavioral and communicational properties and developing game-theoretic models to explain why agents engage in F2F contact. The authors also discuss the role of F2F contact in coordinating economic activities and conclude with remarks on its future importance.This paper argues that existing models of urban concentrations are incomplete without considering the fundamental aspect of proximity: face-to-face (F2F) contact. F2F contact has four main features: it is an efficient communication technology, helps solve incentive problems, facilitates socialization and learning, and provides psychological motivation. The authors develop formal economic models to illustrate these features and their implications for urban economics. They emphasize that F2F contact is particularly important in environments where information is imperfect, rapidly changing, and not easily codified, which are key characteristics of many creative activities. The paper contributes to the understanding of F2F contact by showing its unique behavioral and communicational properties and developing game-theoretic models to explain why agents engage in F2F contact. The authors also discuss the role of F2F contact in coordinating economic activities and conclude with remarks on its future importance.