In the early 20th century, steel baron Andrew Carnegie donated approximately $5 million to construct more than 60 public library branches throughout New York City. These centers of knowledge didn’t just hold books; they also housed a custodian, who lived inside a hidden apartment tucked above the building. These tenants shoveled coal throughout the night to keep the furnaces running. But as heating technology improved, many library custodians retired or left, and their residences were repurposed.

Among the library’s current branches, 32 once contained apartments, but only a handful of the living spaces remain today. Now, one of these relics of the past has been converted into a vehicle of the future: It’s a teen center and programming space, designed to nurture adolescents’ interest in technology.

The teen/tech center is housed on the third floor of the NYPL’s branch in Washington Heights, a neighborhood in Upper Manhattan. The building reopened in 2014, following an extensive renovation. But for years, one of its rooms—the home of the building’s former custodian, Raymond Clark—remained closed off. Now, thanks to a $4.4 million renovation project, its doors were opened to the public for the very first time this past week.

The newly renovated third floor will be used for after-school programs, media and computer programs, and general use. There are also facilities and equipment for adult learners. On Friday, December 2, the space celebrated its official opening with a ribbon-cutting ceremony. Present were New York Public Library president and CEO Tony Marx, along with city politicians who supported the project. Also there was Ronald Clark, Raymond Clark’s son, who lived in the pre-converted apartment during the 1970s.

“This floor had not been used for decades,” Marx joked in a speech delivered at the ribbon cutting. “This is New York City. We can’t have unused real estate.”

As for Ronald Clark, he reflected on what it was like to spend his formative years living in a library. “It was a life-changing experience for me,” he said. “I was the first one of my family to graduate from high school. To be able to go downstairs at any time of the night and open a book and read on any subject that my mind had curiosity about was what changed my whole life. It led me to go on to college.” He said he thinks his old home will be a great new spot for teens.

As of right now, only 13 vacant NYPL apartments remain. Five are slated for renovations, including locations in the Bronx, Harlem, Upper Manhattan, and Staten Island. As for the Washington Heights branch, check out the pictures below to see what their custodial apartment once looked like, and how it looks now.

THEN...

AND NOW.

All photos courtesy of the New York Public Library.