When the 250-year-old glass-making factory at the heart of Meisenthal, a village in Northeastern France, closed its doors in 1969, it didn’t stay empty for long. Local creatives soon moved in, claiming parts of the one-hectare complex — which had first risen to fame for its collaborations with art nouveau innovator Émile Gallé — for a mix of formal and informal uses. Before long, they had repurposed areas for a glass museum, a cultural space known to host the occasional rock concert, and the Centre International d’Art Verrier (CIAV), which is dedicated to promoting the region’s historic skills in France and abroad.

Fast-forward to 2014, and the architects at New York’s SO – IL won a competition to unify these many disparate uses and create additional visitor facilities. Deeming the site too convoluted already — not to mention very dilapidated in parts — the design firm and its collaborator, Parisian architecture studio FREAKS, refrained from introducing any monumental buildings. Instead, they focused on removing a few of the most recent additions to the historic factory buildings and weaving together the remaining components with a poured-in-place concrete surface.

Besides enclosing an intimate new plaza, this canopy also swoops up at several points to form fresh spaces below for ticketing, a café, a shop and extra studios. Rounding out the revamped complex, a pair of simple pitched-roof buildings have replaced two rundown structures to provide a glass-blowing work-shop and additional space for the CIAV, including exhibition galleries.

Rejecting glass as too obvious, the design team chose concrete as its primary construction material. “We liked this idea of a pliable surface that is liquid and then becomes hard, which alludes to the process of moulding glass,” says Florian Idenburg, one of SO – IL’s two founding partners, alongside Jing Liu. Their fluid concept also provides the site with a much-needed sense of flow. “We thought of it like a picnic blanket,” Idenburg says of this core intervention. “It’s an undulating plane that unifies these different buildings into one landscape.”

Though the architects initially intended for the roof to be entirely walkable, the desire for more height led to a steep portion that remains off-limits. While construction proved challenging for the contractor, Idenburg says he has grown to appreciate some of the project’s cruder details as intrinsic to its identity. “We’re not trying to make a Tadao Ando structure,” he says, smiling. “This is very much a working building.”

Nevertheless, there are some masterfully crafted interior moments, including a refurbished great hall that can accommodate anything from intimate 500-seat black box theatre performances to 3,000-person concerts. The slender floating spiral staircase that cascades through the visitor centre is an exquisitely poured piece of concrete beauty.

The final phase of the project involved renovating the museum and its unique curved roof and internal lattice-like structure. But as a “continuously evolving assembly of buildings that have to accommodate changing technologies and techniques,” Idenburg says, the site will never be complete in any conventional sense. Rather, he sees his practice’s intervention as one of many and believes that it will look best in a couple of decades, “when it is fully embedded and other transformations have also taken place.