[ahomescu1]

London and Berlin have a lot of people in general, from different fields (finance and government as much as tech). Is the number of programmers/capita higher in those two cities than average? I think Silicon Valley is the highest you can get (that's my guess at least).

EDIT: IMHO, the closest thing Europe has to these is actually Zurich: it has top universities, money and big companies all in a small geographical area.

[justincormack]

Zurich is a tenth the size of silicon valley by population though, and it is a big financial centre too. There are other comparable tech-specific places, like Sophia Antipolis, Toulouse.

By github usage, which seems a decent proxy [1], London is second after San Francisco, followed by Paris, and Berlin is only 7 (much smaller city though, so density could be higher).

[1] http://www.itworld.com/cloud-computing/376551/where-world-ar...