Creative firms and creative jobs are characterized by their tendency to concentrate in the space (Scott 2005; Lange et al. 2008), forming geographical clusters and creative cities (Florida 2002), nourished by "situated creativity" and creative networks (Staber 2008). A creative cluster is defined as a place that brings together (a) a community of 'creative people' (Florida 2002) who share the same interest in novelty but not necessarily in the same subject; (b) a catalyzing place where people, relationships, ideas, and talents can spark each other; (c) an environment that offers diversity, stimuli, and freedom of expression; and (d) a thick, open, and ever-changing network of interpersonal exchanges that nurture individuals' uniqueness and identity" (De Propris et al. 2009).
In this context, there is a growing interest in the study of the patterns of spatial location of creativity and its role in local and regional development. Although many contributions have focused on the localization and geography of the "creative class" (Florida 2002; Clifton and Cooke 2010; Asheim and Hansen 2009; Boschma and Fristch 2009), there are few studies on the concentration of the "creative industries" (Lazzeretti et al. 2008) to enable a comparison between the several typologies of European and extra-European creative industries (Flew and Cunningham 2010). Furthermore, there is a lack of quantitative studies focusing on the reasons for the clustering of creative industries.
This article explores the reasons for the clustering of creative industries, focusing on four complementary approaches - culture and heritage, agglomeration economies, related variety, and the creative class - and developing a comparison between two countries through an econometric model with the intention of making some generalizations. The two countries selected for the analysis - Italy and Spain - are not understood well enough from the point of view of the creative industries and are characterized by important endowments of cultural artistic heritage and by different patterns of spatial clustering of creative industries.
The main results showcase the existence of some common determinants of the clustering of creative industries, with the human capital, the creative class, and the agglomeration economies being the most important. Urbanization economies and the related variety are particularly important in Spain, where the creative industries cluster in the core of the largest metropolitan areas. In Italy, where the creative industries are more distributed across the territory, forming networks of medium-sized cities, the district-based localisation economies are especially important, as well as the presence of cultural and artistic heritage.
The paper is divided into six parts. After this introduction, the second section surveys the literature on the determinants of the clustering of creative industries. Section three focuses on the methodology for measuring and mapping creative industries in Italy and Spain. Section four deals with an econometric model of the determinants of the clustering of creative industries. Section five present the results. The work ends with some concluding remarks.
2. THEORETICAL FRAMEWORK
Culture, arts, and heritage
One of the first explanations of the clustering of creative industries came from the field of "Cultural Economics" (Towse, 2003). Studies on cultural economics and those on clusters and cultural districts have intensified, creating a rich and interesting mass of literature. Among the many studies of cultural economy and arts management, in parallel with the interest in various cultural sectors (Throsby 2010), the debate has recently been extended to the implications of creativity and culture as a "flywheel" of local economic development (Cooke and Lazzeretti 2008).
Cultural heritage includes historic places, buildings, monuments, paintings, and artefacts and is the reflection of intangible historical aspects of the local culture (traditions, customs, language, lifestyle, etc.). Heritage influences the creative industries from two points of views: first, art, culture, beauty, and history affect the perceptions and attitudes towards creativity; second, by carrying out activities in respect of the conservation, enhancement, and economic management of these resources (Camagni et al. 2004). The "cities of art" like Florence in Italy or Seville in Spain are good examples (Cooke and Lazzeretti 2008).
Sometimes, these elements are related to the historical role of the place as a regional, national, or international capital. The territorial contexts are multifarious, and the fundamental role of forms of clustering is emphasized: from cultural districts (Frost-Kumpf, 1998) to cultural clusters (Mommaas 2004), to creative cities and, lastly, to cultural quarters (Hall 2000).
Notwithstanding the importance of the presence of cultural resources in the territories, the basic reasons for the clustering of creative industries are still recognised based on the traditional concept of "agglomeration economies" (Trullén and Boix 2008; Campbell-Kelly et al. 2010). Agglomeration economies can be broadly defined as advantages in costs or quality due to the spatial concentration of productive resources and actors (population, firms, institutions, and other collective agents). Agglomeration economies are classed as either internal or external to the firm, whereas external economies are usually divided into localization and urbanization economies. Creative industries are affected by agglomeration economies, which basically act as centripetal forces, fostering the incubation and attraction of creative industries in places with specific characteristics (localization economies) or in large cities and metropolises (urbanization economies) (Chapain and De Propris 2009; Lorenzen and Frederiksen 2008).
Marshallian localization economies are associated with the concentration of many firms of similar characteristics in particular localities. From this point of view, creative industries concentrate to take advantage of the existence of a skilled labor market for these industries, of the existence of local suppliers specialized in other parts of the creative filière, and to benefit from local knowledge spillovers. Urbanization economies are originally related to the concentration of industry in general; to an increase in the total economic size of the city in terms of population, income, output, or wealth; to urban labor market efficiency, flexibility, and skills; to social and productive diversity; and to the density of agents (Glaeser et al. 1992; Florida 2002). Urbanization economies explain the concentration of creative industries since they benefit from the large size or capacity of the local consumption market, from the mixture among uses, and from the variety of activities and people. This generates a dense and varied network of agents that fosters mutual economic and social support and knowledge transfer through cross-fertilization mechanisms, and promotes creation and innovation.
Analysing the more recent determinants of clustering in evolutionary economics and new economic geography, a new evolving paradigm is the concept of "related variety" (Frenken and Boschma 2003). A "related variety" industry is defined in terms of industrial sectors that are related because of shared or complementary competences in a cognitive-based definition (Boschma and Iammarino 2009). In other words, a certain degree of cognitive proximity gives rise to effective communication and interactive learning among different industries that contribute to a higher capacity to absorb innovations from neighbouring sectors though cross-fertilization. In other words, "related variety" means that there exists a relationship between industrial sectors and economic activities in terms of (effective and potential) competences, innovations, and transfers of knowledge.
The concept of related variety has recently been applied to creative industries (Lazzeretti 2009) as particularly active in the process of cross-fertilisation and cognitive relationships among different industries. In this context, related variety is supposed to promote creativity and innovation in local systems due to transversality and spillover processes of innovation in other sectors.
The role of human capital and the creative class
A fourth explanation of the concentration of creative industries is related to the seminal contribution of Florida (2002, 2005) through his concept of "creative class." Florida remarks that some places are poles of attraction for the creative class, and, accordingly, the driving force behind the development of a city turns out to be its ability to attract and retain creative individuals. Florida introduced the theory of the 3Ts (Technology, Talent, and Tolerance), which shifted the focus from the creative industries to the human factor and its creative habitat. The advantages derived from diversity are emphasized, together with the socio-demographic characteristics of the population (the bourgeois-bohemian or "bobo" index) (Florida, 2002). Creativity is a multifarious factor, a resource for innovation, but also a competitive advantage associated with culture and territory and a factor in attracting and developing creative industries.
The differential characteristic of creative industries is the "creative content," related to the talent and the existence of a creative and educated class. The creative class includes a cohort of professional, artistic, and scientific workers who share a common creative ethos and add economic value through creativity (UNCTAD 2008). Human capital (talent), in the form of a "creative class," takes a prevalent role in the development of creative industries and creative jobs. This point was previously explained by Ciccone and Hall (1996), who assumed the existence of externalities related to human capital in cities. Lucas (1988) remarked that the externalities generated by the exchange of ideas not only depend on the concentration of people in an area, but also on the quality of human capital. Glaeser (2000) reports that access to human capital encourages firms to cluster. Florida (2002 and 2005) associates human capital with talent and highlights that the economic geography of talent is highly concentrated. Thus, human capital externalities explain the concentration of activities, especially of creative activities, in concrete points of the space  .
3. MAPPING METHODOLOGY
3.1. Creative industries
The term "creative industry" is increasingly used in the context of political planning in many countries (OECD, 2007; UNCTAD, 2008) and receives different theoretical and empirical approaches. It can be considered as an evolution of the traditional cultural industries (Towse 2003); other authors focus on new technologies (video, media, software) by analyzing the changes related to ICT (Lorenzen and Frederiksen 2008), the particularities of the production and organisation process (Caves 2000), and the full cycle of production to use (Pratt 2008). The DCMS (2001, p.05) defines creative industries as "industries which have their origin in individual creativity, skill and talent and which have a potential for wealth and job creation through the generation and exploitation of intellectual property."
There is no commonly accepted list of the activities that form the "creative industry," and empirical definitions focus on a wide range of criteria and activities. The DCMS report (2001) considers the creative industries to be advertising, architecture, the art and antiques market, crafts, design, designer fashion, film and video, interactive leisure software, music, the performing arts, publishing, software and computer services, and television and radio. In the absence of a standard, the DCMS definition is used as a point of departure by many contributions that expand the list towards other cultural or knowledge-based activities.
Thus, Hesmondhalgh (2002) identifies advertising and marketing, broadcasting, film, internet, music, print and electronic publishing, and video and computer games as the core of cultural industries and as activities more related to some form of industrial reproduction. Gordon and Beilby (2006) add, in an OECD report, activities associated with artistic and cultural heritage, whereas Eurostat (2008) also includes some cultural, tourist, and recreational activities. The World Intellectual Property Organization (2003) proposes an analysis not very different from that of the DCMS (2001), including traditionally and technologically creative activities based on the intellectual property rights. Howkins (2001) proposed the inclusion of "research and development" as a creative industry. UNCTAD (2008) synthesized most of these contributions.
In this context, there is a group of creative activities that are common in the most relevant contributions. Departing from the contribution of DCMS (2001) and considering the research quoted above, we propose an operationalization of creative industries in NACE codes in Table 1. This permits us to have a proxy already used in the empirical analysis and a reference for cross-country comparison.
INSERT TABLE 1 AROUND HERE
3.2. Creative local systems
After defining a list of creative industries, our goal is to provide some information about the patterns of spatial clustering of creative activity. The empirical research is performed with Italy and Spain as subjects due to our interest in the patterns of the concentration of creative industries in Mediterranean countries, where little research has been performed. Italy and Spain have similar social, territorial, and governmental structures, very similar income per capita, high levels of manufacturing and tourism, are rich in industrial districts, and are characterized by considerable cultural heritage, especially in regard to their collection of UNESCO World Heritage Sites. The main differences come from the geography of the countries and their political history.
We define a territorial indicator of concentration-specialization to indicate if a place is specialized in creative industries and if this concentration is relevant. This implies three choices: the concrete indicator, the territorial unit, and the type and source of data.
The basic Location Quotient (LQ) provides a clear, comparable measure of specialization. It can be used jointly with other criteria (e.g. the lowest number of jobs or firms) to simultaneously ensure specialization and concentration  :
where Lij is the number of employees in the creative industry i in a local production system j, Li is the total number of employees in the creative industry i, Lj is the number of employees in a local labour system j, and L is the total employment in the country. An LQ above 1 indicates that the clustering of a creative industry i in a place j is larger than the national average, so that the local labour systems is specialized in creative industries; in other words, the area is a creative local system.
Sforzi (1997) and Lazzeretti et al. (2008) provide justification for the use of Local Labour Markets (LLM) as territorial units of analysis. Other units (provinces, municipalities) are too large or small to capture socioeconomic processes of creativity over space. LLM contain the area where the population lives and works and form a community of firms and people that can be identified as a local production system. This choice also permits the use of a homogeneous definition of LLM based on daily commuting flows in Italy and Spain (Sforzi 1997; Boix and Galletto 2006).
We use employment (number of jobs) as the basic data for the measure of specialisation-concentration due to two reasons. First, employment is a suitable measure in an industry (or group of industries) where human cognitive activity is particularly important in the form of human capital or creative class. Secondly, we consider employment more appropriate than other indicators, as the number of firms since the small firm size in both countries causes an overweighting of the small firms if the number of firms is used as an indicator of concentration  . Otherwise, we would underestimate large firms and overestimate the impact of small firms mainly present in the two industrial structures of both countries (Clifton and Cooke 2009).
Local labour systems with an LQ of the jobs in creative industries and a minimum of 250 jobs in creative industries have been considered as creative local systems (CLS). This procedure identifies 29 CLS in Italy and 18 in Spain, and the figures give evidence of the high concentration of creative industries in these CLS.
In Italy, where the LQ ranges from 0.1 to 2.5, CLS represent 5% of the LLM, but have 53.5% of the national employment in creative industries (470,000 jobs). In Spain, the LQ ranges from 0.04 to 2.1 and CLS add up to 2.2% of the local LLM and 63% of the creative employment (423,000 jobs). In both countries, the Gini index of creative industries, even if weighted by the total employment, exceeds 0.75.
Figure 1 presents CLS for Italy and Spain in 2001. Creative industries are less concentrated in Italy, though they are present mainly in the centre and north of the country in big cities like Rome, Turin, Milan, Florence, Trento, and Padua. About 16% of Italian jobs in the creative industries are located in Milan; Roma, 13%; and Torino, 6%. In Spain, they are very concentrated in a few CLS in Madrid, Barcelona, Basque Country-Navarre-Rioja, and Galicia, as well as Valencia and Seville. Madrid accounts for 30% of jobs in the Spanish creative industries and Barcelona, another 15%, which gives evidence of this high concentration.