Shortly after his entry to the 1921 Friedrichstrasse competition, Mies produced a second project for a high-rise office building.  It is, again, an experiment in glass.  The plan is highly inflected, this time not angular but undulating, a perimeter of tangential circles that more or less extend to the property lines of what appears to be a tight urban plot.  Two circles on opposite sides are packed with stairs, elevators and other services.

If you ask me, this plan looks a little like a fish, with the tail flattening towards the back of the site and the head projecting forward, as the plot narrows.

This time there is a model.  The structure is reduced to a series of (steel?) floorplates thirty stories high, evenly spaced and with not even the slightest inflection at the top or the bottom.  There are only a few columns at the center of the projecting circles.  After that, the glass appears as a continuous skin wrapping the structure.  There is an indication of very thin vertical mullions but otherwise the job of the skin seems to be little more than to enclose the structure in all its nakedness.

Lest you think that the architect is engaging only in a geometric or even technical exercise, the model includes its surrounding context in the form of generic buildings of the old city (the bachelors?) about six stories tall, with their characteristic fenestration and pointed roofs.  It seems pretty clear that Mies is here pondering the role of this new architecture within the fabric of the city.