That the ark was in the temple unto this day, means somewhat more, than the mere literal sense. Most probably Ezra wrote this book of the Chronicles; at which time Solomon's temple was destroyed. I rather think Ezra had a spiritual meaning in the expression; and that the phrase is intended to say, that the ark, that is, the presence of the Lord, is with Israel to this day. How delightful to consider, Jesus is with his people always, even unto the end of the world!
Related Commentaries of 2 Chronicles 5:9
2 Chronicles 5:9
9 And they drew out the staves of the ark, that the ends of the staves were seen from the ark before the oracle; but they were not seen without. And there it is unto this day.