This study is a critical reevaluation of the conceptual basis of Mies van der Rohe's use of tectonics. It concludes that Mies's tectonic concepts developed in four phases, and that each phase emphasized specific aspects of his Transcendental thought. It determines that each phase specifically embodied the dialectical arguments of his writings during that phase. The sequence of these tectonic concepts reflects Mies's development from a representational to an ontological understanding of tectonics, and reveals his return to representational tectonics at the end of his life.