Jubilees 10:26
25 For this reason the whole land of Shinar was named Babel because there God confused all the tongues of mankind. From there they were dispersed into their cities, each according to their languages and their nations. 26 The Lord sent a wind at the tower and tipped it to the ground. It is now between Asshur and Babylon, in the land of Shinar. He named it the Collapse. 27 In the fourth week, during the first year — at its beginning — of the thirty-fourth jubilee [1639], they were dispersed from the land of Shinar.
Tanchuma Noach 18
MidrashThe Holy One, blessed be He, thereupon declared: You evil men, because you have sinned with the words Come, let us, I shall confound you through those very words, as it is said: Come, let us go down there and confound their language (ibid., v. 7). R. Hiyya the son of Abba said: One third of the tower they erected was consumed in fire, another third was swallowed into the earth, and the remainder was left standing. Yet if one climbed to the summit of the remaining third, the palm trees in Jericho below appeared no larger than grasshoppers.
Notes and References
"... There remained only to ask what finally happened to the tower, which, according to verse 5, had not only been started but perhaps even completed ('And the Lord came down to see the city and the tower, which the sons of men had built'). The Bible says nothing of its fate. God makes the speech of the builders unintelligible and scatters them over the face of the earth, but the tower itself is not mentioned again, and one might presume from the text that God left it standing where it was ... Interpreters thus concluded that the tower was left as an unfinished monument, a view that seemed to confirm the claim of some that this or that half-destroyed or unfinished structure in the ancient Near East was in fact the abandoned tower. Indeed, if the tower now lay in ruins, perhaps it had not merely been abandoned, but destroyed ..."
Kugel, James L. The Bible as it Was (pp. 128-129) Harvard University Press, 1998