 The findings of this dig allowed Wilhelm Dörpfeld, then director of the German Archaeological Institute, to assert that there existed a distinct substructure to the original Parthenon, called Parthenon I by Dörpfeld, not immediately below the present edifice as had been previously assumed.Dörpfeld's observation was that the three steps of the first Parthenon consisted of two steps of Poros limestone, the same as the foundations, and a top step of Karrha limestone that was covered by the lowest step of the Periclean Parthenon.This platform was smaller and slightly to the north of the final Parthenon, indicating that it was built for a wholly different building, now completely covered over.