He said to the Levites, who instructed all Israel and who had been consecrated to the LORD: “Put the sacred ark in the temple that Solomon son of David king of Israel built. It is not to be carried about on your shoulders. Now serve the LORD your God and his people Israel. 2 Chronicles 35:3

The last time the ark is mentioned is in 2 Chronicles (and 1 Kings) when Solomon places the ark in the temple, where God it should be. What happened to it?

So they brought in the gold goblets that had been taken from the temple of God in Jerusalem, and the king and his nobles, his wives and his concubines drank from them. Daniel 5:3

Some say Babylonian invaders took it when they destroyed Jerusalem (Daniel 5:3 mentions holy objects taken from the temple) . Others think Egyptians stole it (the Indiana Jones theory) or the Romans in 70 AD.

God required that the ark be in the temple at all times. Without it, the temple could not be opened for business. It should have been in the temple when Jesus was there, though Jesus never mentioned it.

Another thing, when the Philistines tried to steal it, it disrupted their population and caused havoc. No nation would want it! When people touched it, they died. Who would want to open it?

The only other time we see the ark is in Revelation, talking about heaven.

Then God’s temple in heaven was opened, and within his temple was seen the ark of his covenant. And there came flashes of lightning, rumblings, peals of thunder, an earthquake and a severe hailstorm. Revelation 11:19

If it were found now, it would be worshipped and treated like an idol. Wherever God hid it, it’s safe and best left untouched.