If you’ve ever taken a ride on the New York City subway, you’re familiar with the musty stations, the feeling of bodies packed into crowded cars, and the desperate rush to make an overcrowded train. You’ve probably caught a glimpse of an enormous rat scurrying among the garbage on the tracks.

But when Philip Ashforth Coppola descends into the subway, he sees something different: exquisite mosaic artworks, some of which are more than a century old.

For the last 40 years, Coppola has meticulously documented every subway station in New York, drawing every mosaic mural, sign, and detail. To date, he’s drawn 110 stations–right now, he’s working on the stretch of the Lexington Avenue line that runs between Grand Central Station and 106th street. Coppola has self-published six volumes of his work, including his sketches, notes, and history that he’s dug up on the designers and architects behind the stations, in a series called Silver Connections. Some of the editions had only 100 or so copies made, and they were bound by hand.

After decades of obsessively documenting the subway system, Coppola is finally getting his due. Princeton Architectural Press is publishing the first commercial version of his drawings for the general public in a volume called One-Track Mind: Drawing the New York Subway. The book pays homage to Coppola’s labor of love and presents a selection of his sketches of the most iconic art in the New York City subway system.

As the book’s editors Jeremy Workman and Ezra Bookstein explain, the intricate mosaics that Coppola has documented weren’t just decor, even though they’re certainly beautiful. When the subway opened in 1904, its planners knew they had an uphill battle to convince people to ride it. “It was like, you’re going to go underground at high speed in a crowded car? It was like going on a roller coaster,” says Bookstein.

The art, some of which resembles rich oriental rugs and statues, was designed to elevate the experience of going underground. Coppola points to the mosaics at 110th Street and Lenox, where a large section of the wall is covered in bright tiles featuring floral chains and rings–it truly looks like a tapestry. Borough Hall in Brooklyn is another example of this tactic at work: There are rich motifs of flowers, ribbons, and even victory wreaths–all of which have survived for more than a century.

The wonder of Coppola’s work is that he reveals these details to everyone–even those who ride the subways daily but likely don’t notice them or have any idea about the history behind them. “Even if you’re not interested in the nuts and bolts of subway design, people were just thunderstruck when they saw [Coppola’s] artwork,” says Workman, who did a documentary on Coppola in 2005. “It reminded them of art they had seen themselves and maybe didn’t notice. We thought that was a powerful message: reminding people of the beauty that’s right in front of their eyes.”