The megaregions of Europe, from The Rise of the Mega Region (PDF), a paper by Richard Florida, Tim Gulden, and Charlotta Mellander.
Accoring to the authors:
Europe’s largest mega-region is the enormous economic composite spanning Amsterdam-Rotterdam, Ruhr-Cologne, Brussels-Antwerp, and Lille. Housing 59.2 million people and producing nearly $1.5 trillion in economic output, this megaregion’s production exceeds Canada’s and as well as China’s or Italy’s. Next in size is the British mega-region stretching from London through Leeds, Manchester, Liverpool and into Birmingham. This mega-region is home to 50 million people and responsible for $1.2 trillion in economic output. The Italian mega-region stretching from Milan through Rome to Turin is a leading center for fashion and industrial design. 48 million people produce some $1 trillion in output, making it the 3rd largest economic conglomerate in Europe and the 7th largest in the world. In Germany, the mega-region encompassing Stuttgart, Frankfurt, and Mannheim is home to 23 million people. To the west is Greater Paris, a mega-region of 14.7 million people accountable for $380 billion in LRP. The bi-national Euro-Sunbelt mega-region (rank 11), which stretches from Barcelona into Marseille and then Lyon, claims some 25 million people who produce $610 billion in LRP. Vienna-pest ($180 billion in LRP), Prague ($150 billion LRP), Lisbon ($110 LRP), Scotland’s Glas-burgh ($110 LRP), Madrid ($100 billion LRP) and Berlin ($100 billion LRP) round out the list of Europe’s mega-regions.
They make the interesting observation that though the European megaregions are comparable in size to those in North America, they are anchored by urban cores that actually tend to be smaller (with the exceptions of Paris and London). So the megaregional designation seems especially pertinent to the conurbations of Europe.
Can I just say, though, that compared to "Cascadia" and the "Texas Triangle," some of these megaregions' names are a bit lacking? I mean, "Am-Brus-Twerp" sounds like some exotic sort of polyp. How's about we change that to "Teutonia," or "The Land of the Very Tall Industrialists" or something? The strikingly uninspired "Lon-Leed-Chester" could be changed to "Teatown." "Rome-Milan-Turin" would sound much better if it were called "Berlusconi's Funland" (or alternately, "Italy"). And while we're at it, why don't we just go ahead and change Berlin's name to "Jelly Doughnut."