The elegant building of the Ionic order is called, according to later literary sources, Erechtheion from the name of Erechtheus, the mythical king of Athens. The construction started before the outbreak of the Peloponnesian War (431 B.C.) or after the conclusion of the "peace of Nikias" (421 B.C.) and was finished in 406 B.C., after the interruption of the works because of the war.
The peculiar plan of the building is due to the natural irregularity of the ground and the need to house the ancient sacred spots: the salt spring, which appeared when Poseidon struck the rock with his trident during the contest with Athena over the patronage of the city, the trident marks and the tombs of the Athenian kings Kekrops and Erechtheus.
The Erechtheion consists of a rectangular cella divided by an interior wall forming two sections. The eastern section, which was at a level at least 3 meters higher than that of the western, was dedicated to Athena Polias and housed the xoanon, the ancient wooden cult statue of the goddess. The western section was divided into three parts and was dedicated to the cult of Poseidon-Erechtheus, Hephaistus and the hero Boutes.
At the north side of the cells there is a magnificent porch with 6 Ionic columns. The bases and capitals along with the frame of the doorway leading to the interior of the cella, have elaborate relief decoration, while the ceiling coffers were painted. The famous Porch of the Maidens (Korai) or Caryatids dominates the south side of the building: six statues of young women, standing on a podium 1.77 meters high, support the roof of the porch, which was part of Kekrops' tomb above the ground.
At the upper part of the building is a frieze of grey Eleusinian stone to which relief figures of white Parian marble were attached. Today they are exhibited in the Acropolis Museum.
Around the end of the 1st century B.C. the Erechtheion was repaired after a fire. During the Christian period it was transformed into a church, while in the Ottoman period it was used as a house. In the first years of the 19th century Lord Elgin carried off the third Caryatid from the west (Kore C) and the column of the northeast corner of the building. Today they have been replaced by copies, as well as the rest of the Caryatids.