When it was completed in 1855, the Smithsonian Institution’s Castle represented the grand ambitions of a revolutionary education organization. With its library, lecture halls, laboratories and exhibition spaces, the James Renwick-designed building on the southern side of the Mall welcomed both ordinary Americans and educated researchers.

The red sandstone Castle — known as such for its ornate stonework and towers — was not only the Smithsonian’s first building, but also a physical representation of the broad range of its activities: hands-on learning, museum conservation, art and science exhibits and educational seminars.

“It’s the original building, and it’s what most people think of when they think of the Smithsonian,” says Albert Horvath, the Smithsonian’s undersecretary for finance and administration.

The Castle was a jewel in its heyday, but it has been falling into disrepair for years and is now mainly an office building, providing space for about 200 employees. A leaky roof and porous exterior have led to widespread water damage. Last year, there was an electrical fire; the year before that, stones fell off its exterior. And this fall, an outbreak of mold — not the first — forced the evacuation of more than 30 employees.

Preservationists blame the museum’s leaders, saying they long have neglected the National Historic Landmark. Smithsonian documents show that the Castle’s restoration has been considered for almost 20 years.

“They are not museum people, they are university people and they don’t care about keeping the buildings up,” says James M. Goode, former curator of the Castle and author of six books on Washington architecture. “The Castle is the icon of the institution. It should be the primary focus, and it is falling apart.”

Its long-delayed renovation represents the ongoing tension within the world’s largest museum system to balance preservation with modernization, says Elsa Santoyo, an independent consultant who has worked with the Smithsonian on many renovations.

“They keep documenting, but somehow when it comes to allocating the resources, [the Castle] keeps getting back-burnered,” she says. “The groundwork is there. They need to address it and stop thinking about it.”

Smithsonian officials say they recognize the building’s physical and symbolic importance and have kept up with repairs as best they can considering their limited budget and maintenance backlog. The institution has 13 million square feet to maintain, and its leaders, forced to prioritize, put visitor needs first, renovating such popular attractions as the National Museum of Natural History’s soon-to-reopen Fossil Hall, the National Portrait Gallery and just about the entire National Museum of American History.

The Castle's main floor has a cafe, shop, restrooms and a few exhibit cases. In 2017, it attracted about 1 million visitors (down from 1.8 million in 2001), a fraction of institution's 30 million total visits that year. Before spending hundreds of millions of dollars on this symbol of its past, museum officials must determine its place in the Smithsonian's future.

“We want to return it to more public use,” Horvath says, citing other organizations that have adapted historic buildings into ceremonial spaces. “It’s an opportunity to do a better job of talking about the stuff we do [outside Washington], about activities that don’t have a public face — to activate it more, tell the story of the Smithsonian, its history.”

A 2002 master plan called for the Castle to “announce the brilliance of the entire Institution” by connecting “visitors, guests and staff.” The document declared that a full restoration should be “a high priority . . . given the poor condition of the exterior envelope.”

In 2014, a more elaborate master plan by the Bjarke Ingles Group was unveiled, envisioning an update for the Castle and the 17 acres surrounding it. The Smithsonian has spent four years and more than $5.5 million developing that project, which is still many years from groundbreaking.

Meanwhile, the institution has focused on dozens of other projects at its 19 museums, research centers and zoo. Since the 2002 plan, the Smithsonian has built two museums — the National Museum of the American Indian opened in 2005 and the National Museum of African American History and Culture in 2016 — and launched major renovations across its huge campus. With the exception of a $55 million renovation of the mostly dormant Arts and Industries Building, the National Historic Landmark next to the Castle, the diverse projects share the goal of appealing to visitors and increasing their numbers.

The Smithsonian spent about $750 million building the American Indian and African American museums, and a similar amount was used to renovate most of its other buildings, including the National Portrait Gallery/Smithsonian American Art Museum, the National Museum of American History and the National Museum of Natural History, three of its most-visited branches. The latest priority is the renovation of the Smithsonian’s most-visited attraction, the 42-year-old National Air and Space Museum, which welcomed about 7 million visitors last year. Congress has awarded about $248 million of the $700 million for that seven-year project to replace the museum’s mechanical systems and stone exterior, while Smithsonian officials have pledged to raise $250 million in private donations to update the exhibition galleries.

The cost and extent of the work at Air and Space has grown as the project has taken shape, but the commitment to repair the museum hasn’t wavered. “That’s why it attracted capital dollars ahead of [the Castle],” Horvath says.

Meanwhile, at the Castle, stopgap repairs are never-ending, employees say. Permanent "swing space" has been set aside to house displaced workers as different sections are fixed. The employees displaced by this fall's mold outbreak are in rented space near L'Enfant Plaza, and it's uncertain whether they will return.

Derek Ross, deputy director of the Smithsonian’s construction division, says many of the problems are common in old buildings that weren’t designed as office space. The especially wet summer and fall overwhelmed the antiquated air-conditioning systems, he says, and overall ventilation is hampered by partitioned interiors.

Ross says the institution has been relentless in addressing the long-standing problems. Windows and air conditioning units have been replaced, he says, and next year, repairs to the exterior stonework will be completed. The plan, Ross says, is to buy time to “give the Castle more longevity” until a full renovation can begin.

Critics and preservationists wonder whether that time will ever come. They are tired of excuses and just want the institution — which has preservation as a core value — to commit to fixing its crown jewel.

“This is a seminal building in the history of America,” says Richard Guy Wilson, an architectural historian at the University of Virginia. “It was built right there on the Mall, in one of the most public spaces of this country, and it helped to show from an architectural point of view the diversity of who we are, and what we have been and how we see ourselves.”

To witness its decline, he adds, “is so distressing. It’s one of the most valuable things in their entire collection.”