Erechtheus, the mythical king of Athens, was raised by Athena and was worshipped alongside her. However, he was also identified with the chthonic demon Erichthonius, who was attached to Poseidon. Therefore, we have two gods contesting the same city. In memory of the contest, the Erechtheion is dedicated to both deities. It was built in the late 5th century (406 BCE) as an elaborate structure divided into two sections. The eastern half was dedicated to Athena Polias, while the western half served the worship of Poseidon. The western section included a saltwater well and a rock with trident marks. According to legend, Poseidon promised the Athenians an eternal water source (necessary for survival), while Athena planted an olive tree, a symbol of prosperity and wealth.