Milwaukee's Mitchell Park Domes, once eyed for possible deconstruction, were named Wednesday a "National Treasure" by the National Trust for Historic Preservation. The group also compiled a new engineering report focusing on preserving the landmark, located at 524 South Layton Blvd., which is scheduled to be released at a 5:30 p.m. task force meeting on the Domes.The National Treasure designation adds the Domes to the list of nearly 80 other sites around the country that the trust aims to preserve and protect. "Anyone who has visited the Milwaukee Domes can appreciate what a stunning and absolutely one-of-a-kind place they are," said Stephanie Meeks, president and CEO of the National Trust for Historic Preservation. "From our work at other icons of modern architecture, like Houston’s Astrodome or Philip Johnson’s Glass House, we also know that inspiring, innovative architecture often requires equally creative solutions. Rather than risk losing this iconic piece of Milwaukee’s heritage, we need a thoughtful, long-term preservation solution for the challenges facing the Domes."Jennifer Sandy with the National Trust for Historic Preservation said the domes are a national treasure for two reasons: they are culturally significant, and their existence is under threat. "I think the domes are fabulous. I live in Chicago. I didn't know they were here. The first time I heard about them I thought, 'How do I not know about this? I have to go visit,'" Sandy said.All three of the domes that make up the Mitchell Park Horticultural Conservatory, constructed between 1959 and 1967, temporarily closed last year because of concerns over falling concrete. Temporary safety netting was installed until officials come up with a long-term plan. All domes have since reopened to the public.The engineering report to be unveiled Wednesday evening is said to lay out a "comprehensive rehabilitation approach" to the tune of nearly $19 million. The trust, which last year put the Domes on a "most endangered places" list, and the Milwaukee Preservation Alliance will launch a public campaign to rally support for the Domes' preservation.Original cost estimates were as high as $64 million. Whether to spend the money and where it will come from has yet to be decided."It's hard to imagine Milwaukee without the Domes,” said Peter Zanghi, President of the Milwaukee Preservation Alliance. "... the Domes are not just beautiful, they are also useful, providing a valuable educational experience to the thousands of students who visit them every year, and functioning as a venue for everything from weddings to live music to model train shows."