See:

https://voxeu.org/article/creativity-and-freedom


"Creativity is often highly concentrated in time and space, and across different domains. In the 15th century, Florence was home to an amazing number of ground-breaking innovators in literature, painting, sculpture, philosophy, and science. At the turn of the 19th century, Vienna hosted pioneers in painting, medicine, biology, psychology, philosophy, music, who all interacted with one another. London in the late 16th century, Paris in the early 19th century, and San Francisco and New York in the past few decades are some other examples of clusters of creativity and innovation in a number of seemingly unrelated domains (Banks 1997, Kandel 2012).What explains the formation and decay of such clusters of creativity? Are they driven by wealth, by specific features of local institutions, or by mere chance? More generally, aside from these exceptional clusters, how concentrated are creative activities in time and space? Is there co-agglomeration of creative people from different fields? And most important of all, what general lessons can be drawn from the historical analysis of creative clusters to foster innovation and the production of creative talent? Given the central role of creativity and innovation in human progress and economic development, knowing the answer to these questions is particularly important."

"In a recent paper, we analyse data on European creative elites born in the 11th to 19th centuries (Serafinelli and Tabellini 2017). We exploit information on the dates and location of birth and death of notable individuals in different creative endeavours (arts, humanities, science, and business) throughout Europe. The source for these data is Freebase.com, a large database owned by Google and coded by Schich et al. (2014), which stores information from a variety of publicly editable sources, most notably Wikipedia. We then match these individual data with a historical data set on European cities and local institutions put together by Bairoch et al. (1988) and by Bosker et al. (2013). Our unit of observation is thus a city in a particular century (between the 11th and 19th centuries).1"


"
Our main variable of interest is the number of famous people born in a city (per 1,000 inhabitants) in any given century. Births are a measure of the local production of creative talent. We also look at the number of famous immigrants (i.e. the number of deaths of famous creatives born elsewhere). Unfortunately, we don't have information on where these notable individuals did their most important work. Nevertheless, the data compensate for this inaccuracy with breadth in terms of time, geography, and disciplines."

"We start by exploring the temporal and spatial patterns in the data, documenting the following stylised facts. First, births of creative people and famous immigrants are spatially concentrated, generally more so than population. Figure 1 displays the spatial distribution of births in the 15th century, the middle of our sample. Darker tones indicate a larger number of births, while population size is captured by the circle diameter. Famous births are shown to be concentrated in a subset of cities, not always those with larger populations. Amongst the large cities, Florence, Nuremberg, and Siena have the most births of creatives, per 1,000 inhabitants."

It's that central corridor again.

"Figure 2 displays the spatial distribution of Births in the 19th century, the end of our sample period. Now many more cities are included in the sample, and the darker tones have shifted to Northern Europe and the UK. The spatial distribution of Immigrants displays similar patterns."

Their conclusion is that it was tied to freedom, i.e. becoming a commune.

"Why is it that becoming a commune fosters local creativity? A priori, several answers are possible. First, the protection of personal and economic freedoms changed the local culture, making it more receptive to innovations and new ideas. Second, the new institutions also changed incentives, through a more meritocratic and inclusive social environment, but also by encouraging works of art and innovations that would enhance the prestige of the city. Third, free cities attracted talented and creative individuals who escaped censorship and persecution elsewhere, and this created role models and facilitated social learning, breeding new generations of innovators. These channels are not mutually exclusive, and it is likely that they are all relevant, although in our research we cannot discriminate amongst them. But, whatever the mechanism, the historical evidence strongly supports the idea that open and democratic institutions breed innovation and creativity."

I personally think there's more to it than that, but interesting nonetheless.