Lerna Heracles killed it, as the second of his labors. The strong Karstic springs remained; the lake, diminished to a silt lagoon by the 19th century, has vanished. Lerna is notable for several archaeological sites, including an Early Bronze Age structure known as House of the Tiles, dating to the Early Helladic period II (2500–2300 BC). The secret of the Lernaean spring was the gift of Poseidon when he lay with the "blameless" daughter of Danaus, Amymone. The geographer Strabo attests that the Lernaean waters were considered healing: Lake Lerna, the scene of the story of the Hydra, lies in Argeia
Lerna Helladic period, shaft graves were cut into the tumulus of the House of Tiles, indicating that the significance of that monument had been forgotten. Lerna was used as a cemetery during the Mycenaean age, but was abandoned about 1250 BCE. Ceramics of Lerna III include the hallmark spouted vessels that archaeologists name "sauceboats", with rims that sweep upwards into a curved spout, as well as bowls with incurving rims, both flat-bottomed and with ring bases, and wide saucers, sometimes with glazed rims, more pleasant for the drinker's lips. Jars and hydria have swelling curves. Painted decoration is sparse; stamped sealing