The 340-ton boulder that is now an art object at LACMA called “Levitated Mass” first had to travel 106 miles, very slowly, to get to its final destination. It took several years to get it there, and involved getting permission from the two dozen localities the rock had to travel through. Along the route, the rock was greeted by enthusiastic bystanders who turned out to watch it pass through their communities. That journey is chronicled in a new documentary.