"Which university did you graduate from?" Hope this helps

Angela's two examples sound the most natural to my ear. "What school did you go to?" from David is also natural-sounding. Starting the sentence with "Which..." is grammatically correct, but unusual enough that it might suggest to some that the speaker isn't fluent. And if someone ever asked me what school I "attend"ed, I'd wonder why they were talking weird.

Is university = school?

Thank you all, guys.

To add to David's list - "Where did you go to school?" or "Where did you go to college?" would also be ways of asking for the same information.