The Metroon, to the south of the Sikyon treasury, was a temple to the Mother of the Gods (Rhea or Kybele). Dating to the 4th century BC, it had eleven Doric Columns on its sides and six at the ends. In Roman times, it was used to house statues of Emperors.

To the west of the treasuries stands the Nymphaeum (fountain) of Herodes Atticus, the philsopher who paid for the building of the aqueduct of the Sanctuary in the 2nd century AD.

To the south are the remains of two prehistoric buildings, dating to between 2000 and 1500 BC.

The Metroon Herodes' Nymphaeum
Prehistoric House and Herodes' Nymphaeum Prehistoric Houses (flanking altar)