The picture with the half-millionth Cub Cadet and the CC Original that Bill James posted was taken at IH's World Headquarters location in the 401 N. Michigan Ave building. If you look at the background outside the windows, you will see the Wrigley Building diagonally across the street and the top of a peer on the south side of Chicago River on the left. IH occupied 10 to 12 floors in the 401 Building for its World HQ organization.
IH/Navistar moved the World HQ Organization out the 401 N. Michigan Building in the later 80's, after the sale of the Ag Line, if I recall correctly and into the NBC building.
Little known triva fact is that the 401 N. Michigan Ave building is located on what was the original site of Cyrus McCormick's first Reaper Works before the Chicago Fire. Not many knew of or realized the historical significance of that fact when IH moved their World HQ's from 180 S. Michigan Ave to the 401 address back in the 60's. In a sense, IH moved back to its roots where Cyrus started the company!
I've often wondered where that 500,000th Cub Cadet is today, if it still exists. Anyone know?