Death Star I's construction was actually started by the Confederacy, back when it was called the "Great Weapon" or "Ultimate Weapon". After the Clone Wars ended, it was turned over to Imperial hands, and they continued work on it.
"Grant Allen [...] had written a book about the Evolution of the Idea of God. [...] it would be much more interesting if God wrote a book about the evolution of the idea of Grant Allen." ~ G. K. Chesterton, The Everlasting Man