Awesome picture Mr. DT.
Check this one out, a worker stands atop the Sears Tower derricks after it is topped out:
tumblr
The guys tumblr says it is "atop the antenna", but seeing as how the tower didn't have antenna immediately after it was constructed I'm willing to be that's the derick he's on. Tumblr here:
http://calumet412.tumblr.com/post/22...the-attenna-of