The city of Butte, Montana, once called ‘The Richest Hill on Earth,’ went from boomtown to mine town to historic precinct in two centuries flat, without a thought given to town planning. It turned out a checkerboard of residential suburbs, tailings and remnants of opencast silver mines enough to cause a city planner to blot his copybook.

When they tried to tame the place and lay down neat arrangements of roads, there always seemed to be an obstruction. Today Butte boasts a classy city grid with classic city gridlocks. Do you suppose the road builder sidelined at this point and said, ‘Never sweat my pal, I’ll go between those trees and tunnel under the tailings.