An interesting series of articles about the history of Israel based on evidence of modern archeology can be read at: http://www.cassiopaea.org/cass/biblewho1.htm
Here is an excerpt from page 3:
"The last mention of the ark in the Bible is a sneering “I told you so” kind of comment by Jeremiah who writes:
'And it shall be that when you have multiplied and increased in the land in those days, says the Lord, they shall no more say, The ark of the covenant of the Lord. It shall not come to mind, nor shall they remember it, nor shall they miss or visit it, nor shall it be repaired or made again.'
"That is certainly a bizarre dismissal of simply the most important item in Jewish history! (At least, according to the Bible.) We will soon see why Jeremiah had this attitude toward the ark. But, the point is, he is clearly talking about it in terms that indicate it had been broken or needed to be 'made again.' Almost certainly, this suggests that the Babylonians destroyed the ark that existed at the time of the kingdom of Judah along with everything else. What is strange is the implication that it was not of sufficient value for them to even cart it off or it would have been mentioned in the objects that were specifically named as having been taken from the temple. And for those who might wish to think that the lack of mention indicates some major secret or conspiracy, allow me to point out all the many confabulations that exist in the Bible have one single objective: to inflate the importance of Yahweh. They do this by using anything and everything as lessons to whip Yahweh’s people into line. If there was any way whatsoever that the loss of the ark could have been used to induce guilt, I think it would have been. What seems clear is that a substitute ark was all that existed in Judah from some point in history. Thus, at the time of the exile, the loss of this substitute ark was no big deal."
Dave