[Verginius Rufus]

Gen. 10.25 and I Chron. 1.19 seem to put the Tower of Babel at the time of Peleg, who was 5 generations before Abram/Abraham according to Gen. 11.18-26.

Obviously this is much earlier than Nebuchadnezzar who lived in the 6th century B.C.

Gen. 11.2 describes the location of the tower as in "the land of Shinar." Shinar is said to be equivalent to Sumer. Babylon was not in the part of lower Mesopotamia inhabited in early times by the Sumerians but further north in the area inhabited by the Semitic-speaking Akkadians. Maybe the term "land of Shinar" had come to be used loosely.

[Engraved-on-His-hands]

Babylon is much closer to ancient Sumer (UR, Uruk, Eridu, etc.) than it is to the centers of Assyrian dominance (Nineveh, Nimrod, Khorsabad). A passage in Daniel would seem to indicate that Babylon was assumed to be part of Shinar.

In the third year of the reign of Jehoiakim king of Judah, Nebuchadnezzar king of Babylon came to Jerusalem and besieged it. And the Lord gave Jehoiakim king of Judah into his hand, with some of the vessels of the house of God; and he brought them to the land of Shinar, to the house of his god, and placed the vessels in the treasury of his god.
(Daniel 1:1-2)

Also, etymologically, "Babel" and "Babylon" are very similar in form, especially when you consider the absence of vowels in ancient Semitic languages. Also, in Ezekiel's prophecy of Gog and Magog, Magog (contrary to speculative modern views that it refers to modern countries such as China or Russia) almost certainly refers to Babylon. There is also a very good argument (which I won't go into detail here about) that "Magog" is an atbash (a type of word play) for "Babel" (similar to the atbash used in Jeremiah 51:1 for "Chaldea").

It would seem that the significance of the Etemenanki with regard to the Tower of Babel is that the Etemenanki was built on the foundation of an earlier ziggurat that would seem to date back possibly to the third millennium B.C. The less than typical tower-like proportion might also be of significance.

None of this is proof positive, but its possible correlation with the Genesis record is interesting to say the least.

[Siena Dreaming]

I always interpreted the era of Peleg as the time the earth literally divided...that is, the earth was separated into the continents we have today, not necessarily the time at which the split of languages occurred.