Trigger the Gala Event

 is a quest in the Fallout: New Vegas add-on Dead Money.

Quick walkthrough

 * Assuming you have put all of your companions (Dog/God, Christine, and Dean Domino) into place you must then find the bell tower. I found it because I put Dog/God into place last then from the switching station in Salida Del Sol I simply followed my map marker as much as I could. It is a very long journey and you must fight numerous Ghost People so be prepared.
 * After triggering the Gala Event, Ghost People will pour into the courtyard below the Bell Tower. You basically have to fight your way back. How lovely.