I was struck by his comments on the un-wisdom of many cities' efforts to create their own local silicon valley, that they don't seem to take a critical look at what would make such projects succeed or not.

This essay on his website was interesting - saying maybe you could do it, if you funded a critical mass of startups, "for the cost of a stadium". http://www.paulgraham.com/maybe.html

And I know he wrote later about being impressed by Detroit. (I thought there was a whole essay, but all I'm coming up with is this: https://twitter.com/paulg/status/595736193297457152 )