Sunday, April 22 is Earth Day. More than one billion people around the globe will voice their appreciation for the planet. Golfers everywhere should be among them: What sport has a field of play that partakes of the environment like golf? And because not every site is ideally suited for the game, enterprising developers and designers have had to work in less-than-desirable environments, from industrial eyesores and toxic Superfund sites to despoiled military bases. As the five courses that follow prove, no sport has turned toxic sites into intoxicating sites quite like golf has.