In Deuteronomy 34 we read this statement about the death of Moses. "Moses the servant of the Lord died there in Moab, as the Lord had said. He (God) buried him in Moab, in the valley opposite Beth Peor, but to this day no one knows where his grave is."
If you are a fan of Elvis, you might make a trek to Graceland. If someone is Catholic, they might go see the tombs of former Popes at the Vatican. And if you wanted to honor our fallen soldiers, you might make a pilgrimage to Normandy. This is a way we honor our dead; we visit their tombs. We do this with loved ones and maybe even to revere great men and women or celebrities we admire.
In extreme cases, people even go to such places and turn those tombs into idols, turning reverence for the dead into godlike worship. Moses was a great man. He had faithfully led the people of Israel well for many years and, as a result, many might have been tempted to visit his tomb to honor him; and honor might have turned into reverence and reverence might turn into idolatry.
So God buried Moses. God alone knows where Moses was buried. In truth, Moses wouldn't have wanted anyone to worship him anyway. His whole life was pointed toward the God he served; so why in death would he want people to honor him? He was just a man, just a servant.
Nikolaus Zinzendorf once said "Preach Christ, die, and be forgotten" and while that seems overly harsh; it is truth. Our life here is fleeting and the point of it is to point others to Christ so that our (and their) eternity may be forever with Christ.
So Moses lay in an unmarked tomb. Unknown to all but God. All glory to God, as it should be. Honor not men, but God alone.