What is the relationship between the Tower of Babel and ziggurats?

John Romer (Testament: The Bible and History) says that the Greek historian Herodotus visited Babylon about 450BCE and saw the Tower of Babel, in fact a great brick ziggurat, still served by a large priesthood, as it had been for thousands of years. The ziggurats, huge stepped pyramids, were thought to hold the way to heaven. To the exiled Jews, a hundred years before Herodotus, it must really have seemed almost to go to heaven. The Jews were just one ethnic group among many that were sent into exile by Nebuchadnezzar, so the insular Jews were suddenly confronted by this dazzling Tower of Babylon and the discovery that the world spoke many languages, most of which were incomprehensible to them.

The priests of Babylon were constantly ascending and descending the ziggurat's central staircase. Romer believes Jacob's Ladder in Genesis was no doubt originally the brick staircase of a ziggurat.