Same team of "artists" pulling another ridiculous stunt at the WTC on Marrch 2001.
"127 illuminated windows on the north face of the world trade center"
That probably gave them access to sensitive parts of the building, very useful for someone who wants to plant explosives.
Once again these artists seemed to be very interested in the WTC in 2001.
They even came back to strike a pose before Manhattan minus WTC, mission accomplished.
http://www.meineigenheim.org/videos/media/windows.html