When any project seeks to build on a site that was previously occupied, one of the first things to look at is the question of reconditioning the site. Abandoned, idled or underused industrial or commercial properties are known as brownfield sites, and this includes the former bus barn and shopping center space that is now Allianz Field. The goal was not simply to make it functional as the site of a soccer stadium, but to turn 32 acres of flat, unattractive asphalt into a site that would include over six acres of grass, 1.5 acres of plantings and 197 mature trees.