The Erechtheion, built between 421-405 BC has tall slender Ionic columns and a projecting "Porch of the Maidens" on the South side.
It is located just north of the Parthenon on the Acropolis, and lis named for the legendary king Erechtheus of Athens.
The Erechtheion once contained a statue of Athena, and is thought to have sheltered the place where the saacred olive tree sprang at Athena's command.