The Maharal in Ohr Chadash references a Yalkut which teaches that Nevuchadnezer ensured that nothing from his treasure of plunder would remain after his death. He loaded his riches onto a boat and sank the boat into the sea. The treasure remained lost until Koresh authorized the rebuilding of the Mikdash and Hashem revealed the riches to him for discovery.
The nature of the Mikdash is to reveal that which is hidden. More important than the revelation of physical treasure is the revelation of the riches of the soul which the Mikdash caused to flourish. The power to grow in Torah, avodah, ruchniyus, and reach unimaginable heights is buried within our souls, awaiting discovery. No matter how deep Nevuchadnezer and the destroyers of sanctity try to bury that treasure, our commitment to rebuild the Mikdash will ultimately prevail and bring about its revelation.