“[Mies] has a cardboard model of Park Avenue between 46th and 57th Streets will all the buildings on the Avenue and some going in the blocks and then he has a number of towers for different solutions that he places in the empty place of the old 375 [the Park Avenue address], and this model is up on a high table so that when sitting in a chair his eye [sic] is just level with the table top which equals the street—and for hours on end he peers down his Park Avenue trying out the different towers.”
—from Mies van der Rohe: A Critical Biography, New and Revised Edition by Franz Schulze & Edward Windhorst