The Propylon was constructed a little later than the Classical temple, and was made of marble and poros. It is Doric, distyle in antis on both sides (north and south). A partition wall inside the building has three doorways, of which the middle one is wider and has a ramp. A small rectangular hall is attached on the west wall of the Propylon, while porticoes are erected along the north and west sides of the sanctuary. The north of these porticoes is larger and slightly earlier.