What is a fun event I can plan at University?!

I am applying to be on council in my university. Part of the process is planning an imaginary event for the residence (approx 700 people). I can use the meal hall, lounge and all the hallways, as well as a courtyard. I don't have a budget, so money is not a huge issue. It can be a fundraiser, party, anything. THe only rule is that alcohol can't be involved. Does anyone have any suggestions?