Bordering the Altis, to the north, are a series of Treasury Buildings. These buildings were not banks, holding hoards of gold; they were gems of architecture erected by city-states in honor of their patron gods. When citizens visited Olympia for the Games, they made offerings to their home-gods in the Treasury temples.

                                                     TREASURY OF THE MEGARIANS

                     
The entablature of the Treasury has been restored together with the pediment, on which is depicted in relief a Gigantomachy,made of limestone.The scene, containing five pairs of gods and Giants fighting, is preserved in fragments and only the figure of the Giant in the middle has survived almost complete. He is shown wounded and about to fall to the ground under the blows of Zeus, the whom only a leg is preserved. The other gods would have been Athena and Poseidon on the left and Heracles with Ares on the right.
Sea monsters or serpents were depicted in the two corners of the pediment. Probably from an Eleian workshop. It is dated to the end of 6th c. BC.
The Megarians had attached a shield taken from the spoils of their victory over Corinthians. On the epistyle is the inscription MEGAREON (of the Megarians), which is from the Roman period.