The scene at the fountain was shot on the Warner Brothers backlot. It is the same fountain used in the intro to Friends (1994). It's also very near the Cooper house on the back lot.
The house where the frat party is held is on Warner's Ranch backlot. It is the same house whose back yard was used as the Heck's in The Middle (2009). The front of the house was also used as the house shared by Axl and Hutch: Hutch Axl Pi.