A few months ago we reported on a controversy at the former military base in San Francisco called the Presidio which has just become a national park that is attempting to be financially self-sufficient. Now, there’s an intrigiung sub-plot to the story that concerns a cluster of abandoned military quarters at the Presidio. A plan to tear down the houses has drawn protests from advocates for the city’s large homeless population and spawned a contentious battle between them and Bay area enviromentalists. Living On Earth’s Senior Correspondent Peter Thomson prepared our report.