Although the Games, and the site of Nemea, became Panhellenic in 573 B.C., the physical remains from that early period are scattered and fragmentary. It is only after the Games return ca. 330 B.C. from Argos that we see clearly the nature of the site and the effects of the Macedonian influence.
The Temple of Zeus was the religious center of the site, although since excavations have not been done to the north and east, the frame of the sanctuary on those sides is not known. Immediately to the east of the Temple was the Altar of Zeus - a long and narrow structure where athletes and pilgrims would take animals to be sacrificed. To the south of the Altar was the Sacred Grove of cypress trees which were mentioned by Pindar and Pausanias, and the planting pits for which have been discovered.
South of the trees was a row of buildings which are called Oikoi and which served as embassies for different city-states including Epidauros and Rhodes. These had been built in the earlier phase, but were repaired and used again in the Macedonian period. Some of them had kitchens and dining rooms which must have served the citizens of the individual cities.
Again to the South is the two-story Xenon where athletes were housed during the games, and in a direct line to the west is the Bath where the athletes cleaned up after exercise and competition.
To the West of the Bath, and on the other side of the River was the long, narrow tumulus of Opheltes from the earlier period, but with a pentagonal enclosure from the later period within which were altars and massive remains of sacrifices to the baby-hero.
Although the stadium in the early period was at the base of the tumulus on the east, and the hippodrome along the western side, the former was transferred in the second phase, around 335 B.C. to an area cut back into the Evangelistria Hill about 400 m. to the Southeast.
The archaeological site of Nemea is a well-organized, visitor-friendly park displaying discoveries of major significance. It proudly welcomes students and lovers of ancient Greek culture.
The vision of Opheltes is to unite the Sanctuary with the Stadium so that visitors can move from one to the other just as the ancient athletes did. The ancient road that connected the two is, however, crossed by a modern road that complicates this plan.
Source: wikipedia.org