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 form decorative patterns on some pieces, or rolled scribed cylinders have been used to make banded patterns. Remarkably, banded patterns made with the self-same seal have been found at Lerna, Tiryns and Zygouries. The burning of the House of Tiles brought the Third Period at Lerna to a decisive close; a low round tumulus marked its undisturbed, apparently sacrosanct site. Lerna IV (Early Helladic III) marked a fresh start, not as a fortified seat of central authority this time, but as a small town, with houses of two and three rooms with walls of crude brick set upon stone foundations;