When we had made driveways, we have had a road base brought in first, such as caliche. Then a layer of rock and caliche is added.
I am assuming that you no longer want it as a driveway but instead want a
lawn or other growing area like a food forest or garden?
I am sure someone here on permies can direct you to the proper way to prepare your soil. All I would know to suggest would bring in a layer of topsoil deep enough to support plant life.