Chronicon Paschale s.a. 328: ... and he named the place Augustaeum because he had also set up opposite his own a monument of his mother, lady Helena Augusta, on a porphyry column. (trans. Whitby and Whitby)
Patria II, 15: The Augusteion ... in which Constantine the Great also set up a statue of his mother; for this he called the place Augusteion ...