An update to my previous post Oh, its difficult going to work.... I haven't been able to take him to my office yet :-(. I will certainly show it to him from the outside.
I did find a way to calm him though when I leave for the day. He likes numbers. I have started showing him the clock and telling him that the small needle is at 9, so that means I have to go to the office and I will be back when the small needle is at 6. That has really worked. He gets really happy when he sees me back and right away points to the clock and says that "Papa is back at 6!"