The exact days on which the Panathenaia was celebrated are not altogether clear, with the exception of Hekatombaion 28 (I 28), the day of the great πομπή honouring Athena. In two ancient scholia it is said that Athena's birthday was celebrated on this main day of the festival. This information has often been deemed false, owing to the existence of other, conflicting testimony according to which Athena's birthday was celebrated on the third of each month, a fact seemingly in accord with her epithet of Tritogeneia. The association between I 28 and Athena's birthday has been seen as the result of the confusion generated by I 28 being the third day from the end of the month (τρίτη ἀπιόντος). I argue that the information contained in the scholia is not the result of confusion. Athena's birthday was indeed celebrated on the main day of the Panathenaia. This date was set in stone by Pheidias on the Parthenon's east pediment.