Joshua set up the twelve stones that had been in the middle of the Jordan at the spot where the priests who carried the ark of he covenant and stood. And they are there to this day. Joshua 4:9 (New International Version)
After forty years of wandering, brought about by fear that "we are grasshoppers in their sight," the Israelites finally enter the Promised Land. As part of this final stage in their pilgrimage, the people are to set up a memorial of twelve stones--one for each of the tribes of Israel. God's command was clear on how the stones were to be selected, as well as where they were to be placed. Once again, obedience will mark the relationship between God and His people.
There are a number of miracles involved in this story. First, it is a miracle that a group of slaves would escape the strongest nation in the world at that time. It was a miracle that God's patience did not give out on are "stiff-necked and hard-hearted people." It was a miracle that the Jordan miraculously stopped flowing that night to allow the people to cross. However, it is as important how we respond to these divine interventions, as God's handiwork is itself.
This was to be a "living memorial" for the people of God, so that they could remember the entrance into the land of promise. There is nothing wrong with these monuments, because some are God-directed. The problem arises when we allow them to become idols. The human heart is as fickle and fleeting today, as it was in Joshua's. Nevertheless, it is our unchangeable God who invites into a covenant relationship with Him that demands our love and obedience.