Does the position of keywords in the URL have a significant impact? For example, example.com/keyword/London is that better than example.com/London/keyword?
Truthfully, I wouldn’t really obsess about it at that level of detail. It does help a little bit to have keywords in the URL. It doesn’t help so much that you should go stuffing a ton of keywords into your URL. If there’s a convenient way that’s good for users where you have four or five keywords that might be worthwhile, but I wouldn’t obsess about it to the level of how deep is the URL in the path or, you know, how am I combining it. For example, on my blog, when I do a post I’ll take the first four or five words or two or three words related to that post and I’ll use that as the URL.
You don’t need to make seven, eight, ten, twenty words because that just looks spammy to users and people will probably not click through as much in the first place. So position is going to be a very, very second order kind of thing of keywords in the URLs. I would not worry about that so much as having great content that people want to link to or people want to find out about.
by Matt Cutts - Google's Head of Search Quality Team