A pair of Zambonis cruise up and down the 60,000-foot vacant lot at 3715 Chestnut Place, pushing loose rock along as they go. Loose sediment hits the wind like a small dust storm, but few of the on-site AEG employees huddled at the entrance seem to mind. Aside from two brightly grinning cartoon rhinoceroses spray-painted on a Jersey barrier, the lot looks like a demolition site more than a concert ground.