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 several had central circular hearths. Narrow lanes separated houses. A great profusion of unlined pits ("bothroi") was characteristic of this phase: eventually they became filled with waste matter, bones, potsherds, even whole pots. The pottery, markedly discontinuous with Lerna III, shows a range of new forms, and the first signs— regular spiral grooves in bases and parallel incised lines— marking the increasing use of the potter's wheel. Painted linear decoration in dark glaze on the pale body is characteristic of Lerna IV. Caskey identified early examples of the ware that in Middle Helladic contexts would be recognized as Minyan ware,