Board Thread:General Discussion/@comment-92.233.139.244-20130530214619/@comment-9887604-20130626142128

"They looked with fear at the winged colossus, and from their babblings did the warriors of the Jorrvaskr learn that it was older than even the elves themselves. Of those who wrought it solid from its mother-stone, nothing could be said, but it was known to drive a magic almost as old as Nirn itself, some remnant of the gods' efforts to render a paradise in Mundus before the shattering of Lorkhan." Songs of the Return Volume 7

Even the elves of the 1st era and the Atmorans did not know who created it. However is predates the elves, which pushes its creation into atleast the early Merthic era if not all the way into the Dawn era.