This building was called the Erechtheion (Erechtheum) by Pausanias, but it is not its official name. It is located on the north side of the Acropolis. It went through two building phases.
It is a strange shape with four sets of columnar supports, four levels, and three structural units, each with own roof. The reason for complexity lies in configuration of rock surface and previous terracing in the area, and in necessity of building around various cult spots in one of the most sacred places on the Acropolis. The area contained many signs and remains of Athens' mythical past (salt-water well and trident marks associated with Poseidon).
The interior was thoroughly destroyed in later times and is now very uncertain. It once contained a wooden statue of Athena Polias, a much venerated image. Various other Attic deities were located in this building, including Erechtheus.
The building is an example of Ionic elaboration and elegance; it is a highly decorative building. It has an elaborate north porch and an unusual south porch (Porch of the Maidens). The building was partially reconstructed in 1837-46, and completely rebuilt in 1903-09.