As part of the observation of the 70th anniversary of the United Nations Secretary-General Ban Ki-moon will be speaking at Stanford University June 25th at 3pm. Of course this is because Stanford is such an excellent place (although I am biased since I work here)! Though it is also because the San Fransisco area has played such a large part in the formation of the United Nations.
As you can see here:
If your interested in attending tickets will go fast!