This chapter delves into the various definitions and perspectives surrounding the concept of city centers, providing a broad spectrum of opinions to enrich the reader’s understanding. Through an exhaustive review of successful historical city centers, this discussion identifies and categorizes key qualities and criteria that contribute to their vibrancy and functionality. These characteristics include accessibility, diverse usage, a distinctive identity marked by symbolic elements, spatial compactness, a variety of building types, and the availability of open public spaces. The chapter culminates with an exploration of the spatial systems and hierarchies typical of city centers. Equipped with this knowledge, readers will be able to articulate a clear definition of an ideal city center. Furthermore, the chapter offers a theoretical framework that can be applied to both the revitalization of existing city centers and the creation of new ones, aligning historical insights with contemporary design needs and requirements.