The National Trust for Historic Preservation has stepped into the debate over whether an 1893 amphitheater on the grounds of the Chautauqua Institution should be demolished and replaced. At a news conference Tuesday in Buffalo, National Trust President Stephanie Meeks announced the group has designated the structure a national treasure. She's asking Chautauqua Institution to work with preservationists to come up with an alternative to knocking down the outdoor theater, where scores of historic and modern figures have spoken. While the designation as a national treasure does not carry legal weight, it lends credibility to arguments that the Western New York building is historically important. Leaders of Chautauqua Institution have proposed replacing the amphitheater to increase capacity, handicap accessibility, and safety.