It's worth the trouble. There are resources. I don't know what there is in France, but the United States offers tax incentives to the private sector to encourage it to invest in historic buildings. There's also a federal endowment fund that makes money available to non-profit organizations to encourage them to preserve historic buildings. We're talking about carrots and sticks. Statutes prohibit certain practices, but there has to be funding to encourage conservation. In Canada, there are no national funds or tax incentives at the federal level, two programs that the Heritage Canada Foundation has been encouraging for a long time.
On February 14th, 2008. See this statement in context.