Mass Audubon held a ribbon cutting ceremony outside a historic powder house along the Charles River in Cambridge on Tuesday to announce plans to transform the granite structure into an urban nature center.

“This is the first urban green space that we have partnered on in a new era at Mass. Audubon, where we're focused on providing more green space and more programming to urban communities,” explained Audubon President David O’Neill, speaking to area residents who crowded into the stand-along structure in Magazine Park.

Cathie Zusy recalled sweeping through Magazine Beach Park a decade ago with Cambridgeport neighbors, picking up litter and bottles outside the old magazine building. By all accounts the park was an eyesore.

“When we first got started here, we just couldn't understand how the park could be in such poor condition," she said.

So in 2016, Zusy, a museum curator, formed Magazine Beach Partners to clean up the area, with a goal of turning the building at its core into a nature center.

“It was always our dream for the park,” Zuzy said.

She partnered with local and state officials, including The Department of Conservation and Recreation (DCR) and the City of Cambridge to remake the public space just off Memorial Drive.

Over the years a canoe and kayak launch were constructed and accessible from a new shoreline path. Thousands of new native plantings spruced up what had been barren patches, and the patio and terrace at the rear of the powder house was expanded.

As Magazine Beach was emptied of trash and discarded bottles thousands more people began to use the renovated park, but the building on-site was underutilized, if used at all.

It began as a site for storing munitions in the 19th century and then transformed into a bath house, an MDC garage (formerly Metropolitan District Commission), and, most recently, a largely abandoned structure.

Shortly after its formation, Magazine Beach Partners reached out to Mass Audubon to take over the powder house, said O’Neill. “But we as an organization, we weren't prepared or ready. And then when I joined about a year and a half ago, I got a call from Cathie Zusy and she said, ‘You've got to come down and see this space and see the opportunities that exist here.’ So we did.”

Mass Audubon said the urban nature center fulfills part of its 5-year Action Agenda consisting of three major priorities: Protecting Resilient Landscapes and Promoting Biodiversity; Committing to Inclusive and Equitable Access to Nature; and Taking Meaningful Action Against Climate Change.

During the ceremony, about a dozen people were scattered across the park: a man taking photographs, several people exercising and others sitting along the river’s edge.

Cambridge Mayor Sumbul Siddiqui said while speaking at the event that the new nature center will be an added attraction.

“This park will hopefully be a center of community and culture, and we're really lucky to have a great partner in Mass Audubon," she said. "I have no doubt that they will be incredible stewards of this park and set a high bar for what community engagement can look like."

Mass Audubon plans to start winter programming outside the facility in December and will open the nature center to the public in the spring of 2022.