(8 Elaphebolion) The cult of Asklepios the Healer and son of Apollo was introduced into Athens in 429 BCE from Epidauria and within a short time, He received a temenos on the hillside of the Akropolis next to the temenos of Dionysos. Although not directly associated with Dionysos in myth, He received a festival at or during the time of the City Dionysia this month, possibly because of the efforts of Sophocles, by then a prominent tragic poet. Asklepias’s importance was such that His other festival was held at about the time of another major Athenian festival, the Eleusinian mysteries (Parke, p.135). Michael Lahanas notes that “In honor of Asclepius, snakes were often used in healing rituals. Non-poisonous snakes were left to crawl on the floor in dormitories where the sick and injured slept. Starting about 300 BC, the cult of Asclepius grew very popular. His healing temples were called asclepieion; pilgrims flocked to them to be healed. They slept overnight and reported their dreams to a priest the following day. He prescribed a cure, often a visit to the baths or a gymnasium.”
More about Asklepios: http://www.theoi.com/Ouranios/Asklepios.html.
For information about Modern Asklepeions (centers of healing): http://asclepieion.mpl.uoa.gr/Parko/enchoose.htm
Parke, H.W., Festivals of the Athenians, 1977