In reference to the Ark of the Covenant, Calmet’s Dictionary of the Holy Bible does not say where the Ark of the Covenant is, but suggests instead that it that it will be forgotten.  The old dictionary states:

“The Hebrew word, which Moses employs to denote the sacred coffer, in which the tables of the law were deposited, signifies a chest or box.  It was of Shittim-wood, covered with plates of gold; two cubits and a half in length, a cubit and a half wide, and a cubit and a half high.  On top of it, all round, ran a kind of gold crown, and two cherubim were over the cover.  It had four rings of gold, two on each side, through which staves were put, by which it was carried, Exod. xxv. 10—22.

“After the passage of the Jordan, the Ark continued some time at Gilgal; (josh. iv. 19) whence it was removed to Shiloh, 1 Sam i. 3.  From hence the Israelites took it to their camp; but when they gave battle to the Philistines, it was taken by the enemy, chap. iv.  The Philistines, oppressed by the hand of God, however, returned the Ark, and it was lodged at Kirjath—jearim, chap. vii. 1.  It was afterwards, in the reign of Saul, at Nob.  David conveyed it from Kirjath-jearim to the house of Obed-Edom; and from thence to his palace at Sion; (2 Sam. vi.) and, lastly, Solomon brought it into the temple at Jerusalem, 2 Chron. v. 2.

“It remained in the temple with all suitable respect, till the times of the later kings of Judah, who, abandoning themselves to idolatry, were so daring as to establish their idols in the holy place itself.  The priests, unable to endure this profanation, removed the Ark, and carried it from place to place, to preserve it from the pollution and impiety of these princes.  Josiah commanded them to bring it back to the sanctuary, and forbade them to carry it, as they had hitherto done, into the country, 2 Chron. xxxv.3.

“It is doubted, with good reason, whether the Ark was replaced in the temple, after the return of the Jews from Babylon.  Dr. Prideaux is of opinion, that as the Jews found it necessary, for the celebration of their worship in the second temple, to have a new altar of incense, a new shew-bread table, and a new candlestick, they had likewise a new Ark; and he asks, Since the holy of holies, and the veil drawn before it, were wholly for the sake of the Ark, what need had there been of these in the second temple, if there had not been the Ark also to which they referred?

“Some think that Nebuchadnezzar conveyed the Ark to Babylon among the spoil of rich vessels carried off by him from the temple; others, that Manesseh, having set up idols in the temple, took away the Ark, which was not returned during his reign.  The author of Esdras (2 Esd. x. 22 (represents the Jews lamenting, that the Ark of the Covenant was taken by the Chaldeans, among the plunder of the temple.  The Gemara of Jerusalem, and that of Babylon, both acknowledge that the Ark of the Covenant was one of the things wanting in the second temple.

“The Jews flatter themselves that it will be restored by their Messiah, says, Abarbanel; but Jeremiah (chap. iii. 16.) speaking of the time of the Messiah, says, they shall neither talk nor think of the Ark, nor remember it any more.”