Mies?

Strangely, in some canonical publications of the Modern Movement, some columns disappear from two famous projects designed by Mies van der Rohe… The are famous, precisely because of their structure’s perfection. Is this a Mies’s project? Is the missing structure essential to understand it in this way? Or the picture doesn’t show any doubts about it? The perfectionism which Mies is generally associated with, makes even more fascinating the orchestrated disappearance of some structure elements, some columns, exactly those which are more visible and necessary.