In 'The World Without Us' by Alan Weisman, the author wonders what would happen to our world, New York City in this example, without the human race.
He foresees rewilding (the return of wolves and bears), plants forcing their way through the sidewalk and water damage to the underground infrastructure. "Before long, streets start to crater," he writes, with scarily apt foresight. "As Lexington Avenue caves in, it becomes a river." [...more]