James Turrell' Sky

i saw James Turrell's sky piece at PS1 years ago in winter.  Not until i felt the room was cold, i realized the frame on the roof-top was a real 'open-up' to the sky. I was looking at a real sky!! the air came inside the room!!!  more than live-broadcast. the one i saw was rectangular-shape 'window'.

this circular one is even more amazing.