I spent the weekend in South Beach, Miami, an urban area that was designated a U. S. Historic District in 1979 in an effort to preserve its distinctive and crumbling Art Deco architecture. Nearly a century earlier Wm Morris founded the Society for the Protection of Ancient Buildings in 1877, the precursor of all modern preservation organizations and still a vital force in Great Britain. You can go to their web site and read Morris's founding (and still guiding) manifesto for the organization. Here is an excerpt:
It is for all these buildings, therefore, of all times and styles, that we plead, and call upon those who have to deal with them, to put Protection in the place of Restoration, to stave off decay by daily care, to prop a perilous wall or mend a leaky roof by such means as are obviously meant for support or covering, and show no pretence of other art, and otherwise to resist all tampering with either the fabric or ornament of the building as it stands; if it has become inconvenient for its present use, to raise another building rather than alter or enlarge the old one; in fine to treat our ancient buildings as monuments of a bygone art, created by bygone manners, that modern art cannot meddle with without destroying.