I think it happened to most of the ancient places Critter.
I remember hearing ( or reading ) that there were thousands of such sites at one time, but that a "Manifest Destiny" rule regarded these sites as a threat and most of them were ripped apart and hauled away in the earliest colonial times or whenever they were found after that.
It seems that this Manifest Destiny thing only worked if they were dealing with "savages" who needed civilizing and "church-ifying" in which case it was all perfectly legal to civilize such people to death...claim their land for a christian king, rob them, kill them, steal the resources, etc, all under the guise of "saving" them from the arms of the devil.
But, apparently if you came upon a people who were already "civilized" which means they had settlements/towns, other signs of occupatation or whatever, then they could not be plundered "legally" without declaring some war or something first. So to make this easier on themselves and keep it all legal for the king, they had to destroy any signs of civilization and declare a "barbarian race" as the occupants of the land.
They could then proceed with manifest destiny and take it all for themselves.
So if indeed this was the case, then anything that resembled civilization in the "new world" needed to be erased and the people called "wild" in order to proceed with civilizing them under the direction of the law of the times. But if this was not the case, then I am open to correction in the matter.