This paper revisits the longstanding problem of the urban core-periphery structure through the lens of complexity and network theories. We argue that this relation remains central to urban science, requiring cities to be interpreted as dynamic systems in which urban form and social structure co-evolve through continuous interaction. Building on classical geographical and economic models, as well as developments in complexity science, the study proposes a systemic approach to describe and simulate the emergence of multicentricity. Using Porto Alegre (Brazil) as a case study, we examine how socio-spatial centralities emerge and interact within the urban system. The results suggest that polycentricity is not merely decentralization, but an emergent property of urban complexity shaped by path-dependent dynamics and social inequality. The study contributes to linking Latin American urbanization to broader discussions on emergence, self-organization, and peripheral urbanization.