Love doing this. I've only encountered one that was still around. So many addresses don't even exist anymore, from street changes and razings. Time is interesting. I wonder at times if the same can be said for the Earth in general. Given an ancient civilization like the Sumerians and using them as sort of a place marker, if one could go back tenfold beyond them in the past might there have been other advanced civilizations that simply attritioned or wiped themselves out completely and were absorbed into time. Time is a long time and the Earth subducts and reshapes everything.