I am surprised no one mentioned the messes in Dallas, Texas. Out of all of the cities I’ve driven in, nothing is messed up as bad as Dallas. Here is an image of a mother mess along side its baby mess (courtesy of Google maps):

I’ve been doing mapping for the Georgia DOT lately and that mess called the Tom Moreland Interchange mentioned above certainly came to mind. It is the hardest for me to figure out where to map accidents anywhere I’ve dealt with.