Introduction to the special issue

European urban policy has often been portrayed in the literature as a clear case of ‘Europeanization’ (Carpenter 2013; Dossi 2017; Carpenter et al. 2020; Hamedinger and Wolffhardt 2010; Marshall 2005). This concept relates to that multidirectional process whereby the reshaping of national and sub-national policies under the influence of the EU is accompanied by a bottom-up and even horizontal transfer of knowledge, paradigms and best practices, that are increasingly shared by institutions in a multi-level governance system. In this special issue we largely concentrate on the first type of relationships, the ways in which the planning practices, and local development trajectories, of certain cities are being influenced by the implementation of EU projects. Cities started to be explicitly viewed as key elements of regional development in the European Community at the end of the 1980s. Following the reform of the Structural Funds approved in 1988, the reshaping of regional policy was accompanied by programmes that, for the first time, were specifically designed to stimulate actions in urban areas (Williams 1996). The success of these early initiatives – i.e. Urban Pilot Projects – was essential to demonstrate that the European Union could play a key role in overcoming the development problems experienced by European cities, including the social consequences of economic decline and the environmental challenges of urban areas (Atkinson and Zimmermann 2016). As a result, the subsequent decades were earmarked by growing political and financial efforts from various EU institutions to widen the role of cities within Cohesion Policy. This was first manifested in the creation of different policy instruments directly targeted on cities (i.e. URBAN Community Initiative, URBACT or, more recently, the Urban Innovative Actions), in order to increase the capacity of municipalities to experiment with new planning solutions to face the challenges of urban development. Later, the focus on urban issues and challenges also became embedded in the mainstream instruments of Cohesion Policy, including the Structural Funds, which are the responsibility of regional authorities. This progress led to the acknowledgment that the development of cities and regions are, to some extent, inextricably linked, and to recognise that this symbiosis must be a guiding principle of any future reform of EU Cohesion Policy (McCann 2015; Medeiros 2019). After almost 30 years of widespread interventions in cities and regions there is no clear measure to prove the impact of EU urban policies on regional development and