The earliest baths of the sanctuary are situated near the bank of the Kladeos river. They were named Greek baths so as to be distinguished from the baths of the Roman period. The original structure, which dates to the fifth century BC, was gradually remodeled and enlarged. The Greek baths were probably abandoned in the Roman period when several other bath complexes were built inside the sanctuary.

The original baths built before 450 BC consisted of a simple oblong room (Area I), twenty metres long and four metres wide, with a well at one end from which water was drawn for the athletes' needs. Later, possibly during the fifth century BC, a smaller room (Area II) with small built tubs along the north and east sides was added to it. At the end of the fourth century, another room (Area III) was added to the west; this was lined with bathtubs on three sides and had hot water. The last important remodeling took place in the first century BC when a large apsidal room (Area IV) was built to the south and hypocausts were constructed. The adjacent swimming pool, twenty metres long, sixteen metres wide and 1.60 metres deep, belongs to the first construction phase (fifth century BC). It had five steps on either side, a sophisticated water-supply and drainage, and was paved with rectangular poros slabs. The pool went out of use probably in the first century BC, and was partially covered by the Kladeos baths built to its south a century later. Much of it was washed away by the river so very little remains today.

The monument is closed to the public.