On the eastern side of the temple (front) and on the same axis stands a circular altar. Outer diameter of this altar measures 8 meters and the inner one 5.5 meters, had two doors. On the thresholds, the holes for the hinges can still be seen. The inside of the altar is very well preserved which had been used in the Archaic, and also the sacred place where the animals presented as votive offerings were burned in the Hellenistic and Roman temples.
During excavations, the great amount of ashes foun in the building. It is understood from the masonry of the lower parts of this circular that it was built in the archaic period.
The front part of the temple is encircled with 3.5 meter high protective walls. To diminish the difference of levels in the large area in front of the temple, these walls were built. There are five outlets with staircases in the uncovered portion of these protective walls, each 2.5 meters wide. On the same axis, just opposite the altar the central stairs are situated. These stairs led to the terrace on which stood the votive and gods’ statues.
There are rows of benches next to the stairs along the terrace wall situated in the direction of the south-east end of the temple. These benches extending parallel to the steps of the temple were built in the Hellenistic period, and were the rows of benches for the stadium situated to the south of the temple. Festivities in every four years called the “Megala Didymeia” and torch processions and competitions were arranged. In the center the bases having a hole which marked the starting points of the races, can be seen at the eastern end of the stadium.