ROTTERDAM (NYT NEWS SERVICE ).- Sjarel Ex stood in the basement of the Boijmans van Beuningen Museum, ankle-deep in rising waters, facing a Sophie’s choice.

Rotterdam’s fire chief had told him that the collection of paintings would be destroyed within 30 minutes unless Ex, a co-director of the museum, gave permission to sandbag the library, sacrificing the books.

In the end, the art was saved and only a couple of hundred volumes lost. But the 2013 event catalyzed Ex’s campaign to move the collection. “From that moment on, we were not so very polite about the need to have a new storage facility,” he said.

He fought for this as part of a plan to close the 1935 museum for renovations, which were already under discussion.

But rather than building a fortified “black box” somewhere, Ex said he saw an opportunity to do something radical by opening the museum’s storage to the public while the main building was closed.

“The first plans were that maybe 20 or 40% would be accessible,” Ex said. “At a certain moment, we said, ‘Why don’t we make it entirely accessible?’”

Six years later, the museum is spending nearly 85 million euros ($95 million) on the Depot Boijmans van Beuningen, a glittering, mirrored building. Designed by MVRDV architects, the storage center is in the city center, right next to the museum. The main building is closed for a 234 million euro renovation of its own, set to reopen in late 2025; the Depot will remain.

When completed in 2021, the Depot will contain the museum’s entire collection of 151,000 artworks, as well as curators’ offices, conservation studios, a movie theater, a restaurant and a rooftop garden. Visitors will be able to walk among the storage racks and pull out items, accompanied by guides and guards. Ex hopes it will attract 150,000 to 250,000 people a year.

The Depot represents a shift in thinking about the public’s access to an institution. Ex estimated that about 6% or 7% of most major museum holdings are on view at any moment.

As collections have grown increasingly vast in the past several decades, institutions are seeking to balance two mandates: protecting and preserving works, and sharing as much as possible with the public.

Plans for the Depot have drawn officials from museums in Finland, Norway, South Korea and Sweden to Rotterdam, curious to view it as a model, said Ina Klaassen, the Boijmans’ other director.

In Paris, the museums along the Seine that are vulnerable to flooding — including the Louvre, the Musée d’Orsay and the Musée du Quai Branly — are considering storage solutions that may be partly open to the public. (Officials from Paris have visited to look at Rotterdam’s plans.)

The Victoria and Albert Museum in London is following close on the heels of the Boijmans Depot, with its V&A East storage facility expected to open in 2023. The new space will house about 250,000 objects and 1,000 separate archives, which visitors can explore.

Tim Reeve, the strategic leader of the project, said V&A East would be “an endlessly changing cabinet of curiosities” from the collections of furniture, fashion, textiles and art. He said that visitors could also learn from curators how exhibitions are planned and watch conservators at work.

Other museums have taken small steps toward open access, with so-called visible storage. The Henry Luce Foundation has supported “open study” centers at the Metropolitan Museum of Art in New York City, at the Smithsonian American Art Museum in Washington and at the Brooklyn Museum that allow visitors to see works in storage, usually in curated displays that can be viewed only through glass walls.

In October, the Pompidou Center in Paris said that it would build a depot in the city’s suburbs. The center will be “partly open to the public, so that it can benefit from a new type of contact with the work,” the museum said in a statement. The Louvre-Lens, a satellite of the national museum, in northern France, also has visible storage, with changing collections visible through glass. Visitors can enter by appointment.

Reeve, a deputy director of the V&A, said that the museum wanted to “move the dial” with its new facility. “The idea is really to take down the glass wherever possible, take down the barriers wherever possible.”

“It’s not just an architectural model, or a logistics move,” he added. “It’s a cultural change.”

On a recent tour of the Boijmans Depot construction site, Ex pointed out the crisscrossing staircases that will lead visitors to exhibition rooms and curators’ studios, and structures that will eventually hold glass display vitrines.

He noted proudly that the storage rooms start around 20 feet above sea level — an important consideration in the Netherlands, which is particularly vulnerable to flooding. (He hopes the design will eliminate hard decisions at the last minute.)

Cranes hovered over the building’s exterior, while workers placed mirrored glass plates onto the facade. Reflected on the surface were the main museum building and Rotterdam’s wider cityscape.

“It’s all about the public,” Ex said, as if the symbolism weren’t strong enough. “Bringing the outside in.”

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