There are several well-documented examples throughout history: Vienna at the turn of the twentieth century[1], and the Florence Renaissance during the fifteenth century.

[1]: http://www.amazon.com/The-Age-Insight-Understand-Unconscious...

I'm on my way out and maybe someone else can chime in with more relevant references, but as a starting point, this is something studied at least in business/economics. Wouldn't surprise me to find something similar for the arts/sciences:

http://en.wikipedia.org/wiki/Economies_of_agglomeration http://en.wikipedia.org/wiki/Business_cluster

<Edit>Leave your email in your profile, and after doing some research I will send you info. This is a very good question.</Edit>

Sorry for the late reply. I picked up a coffee table book titled "100 of the World's Most Beautiful Paintings," reading through it, I would quickly Google artists, and found a few lived close to each other and during the same era. I would have to go through it again, but surely I will add it here once I do.

Something more obvious would be Socrates -> Plato -> Aristotle.

Also Einstein's influential TOR work on the Atomic bomb when highly capable scientists advanced the same work in the United states at the same time.

More relevant reading: Where Good Ideas Come From [http://www.amazon.com/gp/product/B003ZK58TA?btkr=1]