The building known as the “Treasury of the Siphnians” is a votive offering of the people of the island of Siphnos to Apollo; the monument is one of the most splendid and richly decorated buildings in Delphi. The visitor walking up the Sacred Way would see the Treasury of the Siphnians beside the Treasury of the Sicyonians and that of Megara. The monument housed all the precious offerings and souvenirs of the glory and wealth of the island of Siphnos. The construction of Treasury is mentioned by Herodote as well as by the ancient traveler Pausanias. According to them, the monument was constructed in the second half of the 6th century b.C.; it is a proof of the immense wealth that the Siphnians had aggregated thanks to the gold and silver mines of the island. They had become so rich that they decided to offer the tithe of the income to Apollo; so they had constructed the Treasury at Delphi. Based on the stylistic features of the sculptural decorations, scholars date the construction of the monument just before 525 b.C., as it is in this year that Siphnos was invaded and looted by the rebels of Samos.

The Treasury is a pretty small, temple-shaped building, made of Parian marble, in contrast to the rest of the monuments of this period which were made of porous stone.  Herodote states that the monument was famous in his times for the rich sculpture decoration, which is one of the best samples of the Archaic sculpture. On the façade, between the two antae, stood two korae, to support the architrave, instead of the usual columns; these sculptures are an excellent sample of the Ionic plastic art of the period. An Ionic-style kymation (a decorative motif imitating a wave) and a nice frieze decorate the architrave on all four sides of the building, depicting episodes of Greek mythology. On the eastern side it is presented the assembly  of the gods at Olympus, who watch the siege of Troia; on the southern side it is depicted the rape of Leucippidae by Dioskouroi; the western side of the frieze presents the judgement of Paris and the northern one, the best preserved, depicts the Gigantomachy. The work is excellent: the powerful expression, the clear lines, the impressive figures and the care of details make this sculpture a masterpiece. The eastern pediment, at the main entrance of the monument, presents the conflict between Apollo and Hercules for the Delphic tripod; a theme pretty common in the art of Late Archaic period. The pediment is crowned by three acroteria: two Victories are depicted at the two ends and a Sphinx at the center.