NEW YORK’S NEWEST CENTRAL circulating library, The Stavros Niarchos Foundation Library (SNFL), had a quiet beginning when it was completed just two months into the pandemic’s start in May 2020. At first the long-awaited renovation of the Mid-Manhattan Library (MML) was only open for grab-and-go book collection and limited occupancy, but now the New York Public Library’s largest circulating branch is proving that libraries are no longer just for hushed studying. In addition to 180,000 square feet of renovated spaces including open stacks, children and teen areas, an adult learning center, and meeting rooms, the building is topped with an attention-getting angular roof and public rooftop space that has become a landmark on Fifth Avenue—and the only free, publicly accessible rooftop terrace in all of Manhattan.

Designed by Dutch architecture firm Mecanoo in collaboration with Beyer Blinder Belle Architects & Planners, the project aimed to add 35 percent more public space to the building, which receives approximately 1.7 million visits every year. The MML was originally located within a former 1914 department store, which it occupied in 1970, and its interior retained many of the spatial constraints and systems of the retail space, including varying ceiling heights, an escalator, and poor ventilation.

One initial focus for Mecanoo founding partner Francine Houben was an opportunity to design a contemporary complement to NYPL’s Stephen A. Schwarzman Building (SASB), located across Fifth Avenue from SNFL. (Mecanoo and Beyer Blinder Belle have collaborated on programming and design across both locations.) That building, designed by Carrère & Hastings and opened in 1911, shares a Beaux-Arts style with neighbors on Fifth Avenue, and the architects used that influence along with neighboring copper clad mansard roofs, as a jumping off point for the SNFL’s signature rooftop design. The other major goal of the renovation was to make use of an unusual floor plan, which had one long leg between 39th and 40th streets where the department store’s loading dock had been.

“We came up with the idea of the Long Room, named after the library of Trinity College in Dublin,” says Houbin. This solution allowed the architects to use the oblong floor plate to create completely browsable and accessible stacks for the library’s 400,000 books and other materials. To house that much media, the team that included Silman as structural engineer devised a plan to create five floors where there had previously been three. “We really wanted to use the columns,” comments Houben, referring to the building’s structural steel frame. The solution was to cut a triple-height void into the floor slabs, 31 feet wide and rising 85 feet from the second story to an abstract ceiling artwork by Hayal Pozanti to echo the famous muraled ceiling of SASB. Now, this linear atrium separates three floors of flexible, daylit reading areas on one side and five levels of book stacks on the other, an efficient solution to balancing the need for a browsable collection and the library’s desire for more public reading room space. Through SNFL’s 40th Street windows, passers-by can see the northern end of the book stacks, visible as a continuous vertical wall of book spines welcoming them to browse.

This alteration required the demolition of the third and fourth floor slabs at the east side of the building, which Silman replaced with four new framing levels for the stacks. The floor slabs adjacent to the Long Room were removed at consecutive levels to create a multi-level open space. Bridges connect the main floor levels to the tiered levels of the Long Room. Another two voids in the ground-level slab, which required simply subtracting the existing floor plate, supply natural light to the lower floor, which houses a Children’s Library and Teen Center.

“The subtractions ended up being more complicated than the additions in a sense,” says Elizabeth Leber, the partner in charge of the project for Beyer Blinder Belle. She describes how one of the more complex aspects of the project was the design of the new floor slabs for the Long Room. Those five floors were constructed with a long-span corrugated metal deck that is perforated for improved acous- tics. “It does all of the work in a very shallow depth and air gets distributed along the walls so we don’t have the drops of ductwork,” says Leber. “It’s a quiet detail and it was down to inches. The whole concept of the Long Room hinged on getting this to work, and therefore the capacity of books.”

Another behind-the-scenes effort to make the Long Room concept come to life involves fire prevention within the vast void space. Because New York building code defines any void that connects more than two stories as an atrium, the design team devised a solution to integrate automatically retracting shutters that can close off the fourth floor. In the event of a fire, that curtain drops down and the void becomes a two-story opening.

Upon entering the library, visitors encounter an internal street that runs from the Fifth Avenue entrance to the welcome desks. The building’s existing structural steel columns became a dramatic element, painted in dark brown and uplit to guide visitors into the library’s public spaces. The columns are also used to structurally hang expansive work and display tables throughout the space. An existing mezzanine level was completely reshaped and hung from the level above using structural rods and columns.

Houben and team knew that no transformation would be complete without making a public facing gesture on the building’s exterior as well. Noting that city rooftops in the United States are often dedicated solely to mechanical equipment, Houben says, “I really wanted to use the roof.” With a design fondly named the Wizard’s Hat for its green chapeau-like form visible from the street, SNFL’s rooftop now supports a flexible 268-occupant conference and event center. An L-shaped roof terrace runs above the 40th Street and Fifth Avenue facades and includes a roof gar den and indoor café.

Silman designed reinforcements of the existing roof framing at various locations to support the loading of the new vertical addition. The new addition itself was designed on a platform of new steel supported on new columns that align with existing column locations. To allow for longspan spaces, the steel-framed addition has columns spaced 20 to 60 feet apart. The floors and sloping roof are supported primarily by a combination of steel brace frames, moment frames, and trusses, concealed within the finishes and the mechanical service levels above. The mechanical levels and the amenities below are topped with the hat, which reaches 184 feet above street level and is clad in factory-painted aluminum panels to mimic the patinated copper roofs of two 1904 Beaux Art rooftops visible from the terrace.

With new sightlines across Fifth Avenue to the Stephen A. Schwarzman Building and surrounding skyscrapers, the SNFL branch is perhaps more at home among its neighbors than it has ever been. Though the library had undergone small renovations in the past, the architects and patrons agree that the building, benefitting from the design flexibility of the original building’s steel frame, is finally living up to its full potential as a community hub. “It didn’t fully become a library until we did this renovation in a sense, though culturally it was beloved,” says Houbin. “It is a testamentto how an older building can be reimagined.”