Arrephorion

A 5th-century BC building on the northwest edge of the Athenian Acropolis, identified by Wilhelm Dorpfeld in the 1920s as the residence of the Arrephoroi -- two aristocratic girls aged 7-11 chosen annually to serve Athena's cult. During the nocturnal Arrephoria festival, the girls carried mysterious sealed chests and descended via a secret stairway in the north wall. Only limestone foundations survive; the structure was deliberately reburied in 2006 to protect it for at least 120 years.