Reduction ad absurdem would have to ask to install a streetlight because it might cast an unfavourable shadow onto a building?
Well, yes, fun though these things are, I think you should. There are a lot of issues involved, I would think: light pollution, drawing crowds, even (at a pinch) invasion of privacy if people were photographing it. And if you add in collecting money to view it .. well, who gets the money? Without your building, there would be no art, so you should get a cut. Maybe they should charge rent for the space to project the show?
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