Here is an idea presented by Perry Stone. He does a better job explaining it, but I will try.
 

In genesis the bible talks about 4 rivers in the garden of Eden, the tigress and Euphrates, and the sidon, and one other, I don’t remember.  The Sidon has been identified as the Nile, which means the garden of Eden stretched from Iraq to Egypt. According to Perry, this would put Jerusalem in the middle.  In the midst of the garden was the tree of life and the tree of knowledge which would place them where Jerusalem now sits.  His theory is that the temple site sits where the tree of life used to grow, and the tree of knowledge sits atop the mountain where Jesus was crucified.  So Christ was crucified on the exact spot where the fall of man took place and since he is the bread of life, his dwelling place on earth should be the spot where Life began and sustained.  Incidentally from Iraq to the Nile is approximately 1500 square miles, and the New Jerusalem will be 1500 square miles.  Just thought I would share.