Undergraduate Schools for Mathematics

I am currently a senior in high school, and I have been studying mathematics for about nine or ten years now in my personal time outside of school. I am not familiar with academia or in general higher education, but I do know that I want to continue studying mathematics or something in a related area.

I am having a lot of trouble pinning down which universities I should consider going to, I don't think I am even ready to start comparing, so despite the 'softness' and vague nature of this question I feel I don't really have any where else to start then by asking which universities should I be looking into for mathematics?

I have read many articles that rank schools according to some criteria, articles with titles like "Top Universities for Mathematics" or "Best Mathematics Programs", but I really want to get the opinions of people who study mathematics frequently. Any school suggestions would be greatly appreciated. I am trying to gather a list so don't hestiate.

I live in California and am willing to go anywhere on the planet, so location is not a problem for me.

Northwestern is a fairly small school with an excellent math faculty, who make a real effort to identify freshmen who are talented in mathematics and direct them into appropriately challenging courses. There is plenty of opportunities for math majors to get to know individual faculty members, do independent studies, write senior theses, take graduate courses, etc.

Waterloo shows up high on Putnam lists, so you might want to consider it.

University of Toronto is great too.

If you are interested in any university in the world, you should definitely consider the UK.

Cambridge has a very strong mathematics programme, developed from a long heritage. Oxford, Imperial College, Kings and Warwick are also very good in the UK.

A comparison website with an international bent is http://www.topuniversities.com/university-rankings/university-subject-rankings/2012/mathematics

Aside from all these "top ten" type of lists and people's opinions, you should find a university which resonates with you personally. You will get the most out of the course if it fits you, not if it is the best programme ever.