I would forget that notion. Where would we build such an enormous physical structure on earth. At a minimum it would be about 350 miles on each side, and more likely about 1500 miles on each side. That would also be the height. This image puts it into perspective:
http://www.tourofheaven.com/eternal/new-jerusalem/size.aspx
Therefore, it is safe to assume that New Jerusalem is a spiritual city.
Philip
The Council at Adam-Ondi-Ahman Will be a Day of Judgment for the Righteous