Does somebody know what was being done here?

In that spot there was always grass but for some reason there was a construction fence around it and the grass was gone a few weeks prior to 9/11 and still looked like that when the event was unfolding. After 9/11 the grass was restored, but does somebody know what was being done there? In my opinion I think something was being built there but I’m not sure if that’s true or maybe it had to do with the cancelled Quebec New York 2001 Exposition, but I’m not sure, I would really like an answer. Thank you.