No matter the weather, Milwaukee locals know where to go to bask in a climate-controlled environment filled with flowering plants, fruit trees, and brightly colored birds: The Mitchell Park Horticultural Conservatory, better known as the Mitchell Park Domes. Completed in 1967 at a cost of $4.5 million, the three conoidal glass domes were built to replace another conservatory on the site. Architect Donald L. Grieb went all out to give the new building its Space Age look, from the 85-foot-tall, beehive-shaped domes to the undulating concrete form that marks the main entry area. When Lady Bird Johnson dedicated the site in person in 1965, she called it “Milwaukee’s exciting new astrodomes for nature.”

Johnson spoke in the Show Dome, meant for flower shows and other exhibitions. The Arid Dome (also called the Desert Dome) re-creates the environment of deserts around the world, including those in southern Africa and South America. And the Tropical Dome holds a carefully curated rain forest and its attendant vegetation, as well as an assortment of birds and fish. Each dome measures 140 feet in diameter at its base, supplying a total of roughly 46,000 square feet of floor space for year-round enjoyment and education. Admission is free for members of Friends of the Domes (a local nonprofit) and the American Horticultural Society, as well as children under the age of 2. “Especially in the colder months here, it’s an escape,” says Guy D. Smith, executive director of Milwaukee County Parks, which owns and operates the Domes.

After 56 years of wear and tear, the Domes need refurbishment. The glass is cracking in places, and leaks abound. Mesh safety nets line the ceilings after a piece of concrete fell inside one of the structures in 2016. The ongoing possibility of demolition worries groups who want to save the Domes, including the Milwaukee Preservation Alliance, Docomomo US/Wisconsin, and the National Trust for Historic Preservation.

The National Trust named the site one of America’s 11 Most Endangered Historic Places in 2016, and worked with the Milwaukee Preservation Alliance to create “Save Our Domes,” a social media and in-person campaign to increase awareness of the threat to the Domes. Since then, the Trust has continued to team with local partners and consultants to find ways to rehabilitate the building, including exploring the potential use of historic tax credits. “We support ongoing efforts to promote a preservation solution for the Domes,” says Jennifer Sandy, a senior field director at the National Trust.