Joshua 4:8-9

8And the children of Israel did so, just as Joshua commanded, and took up twelve stones from the midst of the Jordan, as the Lord had spoken to Joshua, according to the number of the tribes of the children of Israel, and carried them over with them to the place where they lodged, and laid them down there.

9Then Joshua set up twelve stones in the midst of the Jordan, in the place where the feet of the priests who bore the ark of the covenant stood; and they are there to this day.