Every day millions of people step right over manhole covers and pay them little attention. Don’t feel bad about this; they're meant to be ignored. If these pieces of ubiquitous urban industrial design tripped you up, they wouldn’t be doing their job of hiding the city’s underground infrastructure.

The thing is, manhole covers are really, really cool. Especially London's. The city, known for its Victorian-meets-industrial aesthetic, is full of cast iron hatches imprinted with delightful patterns. In the new Pentagram Paper Overlooked, graphic designer and Pentagram partner Marina Willer created a small survey of London’s covers, transforming the functional metal pieces into Day-Glo graphic design. The book offers a colorful tour through the city’s industrial history, as seen through manhole covers.

Coal holes, as they’re often called in London, have a decidedly utilitarian origin story. In the early 19th century, much of London’s heating was fueled by coal. To deliver the stuff to a home’s coal bunker, merchants would remove a cast iron hatch from the street and carry the sacks through the underbelly of a neighborhood instead of dragging them through a house.

Most of these iron covers bear the name of the foundry and location where they were cast. And they’re surprisingly decorative, given their strictly utilitarian function. But despite their industrial-era roots, the visual flourishes were in line with the Victorian era aesthetic. “It’s coherent with the architecture of that period,” Willer says. One, found in Arundel Gardens in Notting Hill, is marked by a flowering pattern. Another, on Doughty Street in Bloomsbury, has an almost fleur-de-lys illustration. Many are imprinted with geometric patterns that were perhaps not intentionally modern, but read that way today.

Pentagram

Willer’s team of designers traversed the city from Islington to Pimlico to search for the most stunning coal holes. They spent more than a year choosing 22 to include in the book, choosing those with especially interesting patterns, beautiful geometry, and other aesthetic flourishes. When they found one the liked, the designers draped it with a sheet of carbon paper, then used a rock to create a rubbing of the pattern. From there, they’d scan the paper and upload it so they could digitally apply the neon colors you see here. “By doing the rubbing you’re as close as possible to the reality of it,” she says.

The colors, clearly a departure from the oxidized gray of the metal, were a deliberate choice. Willer wanted to highlight the beauty of London’s covers, something she says is too often lost amongst the reputation of sooty London. “Industrial England feels quite ornamental,” she says. “When you put the color on it you emphasize the paradox. Industrial isn't just a brutal, masculine, functional thing. It actually has a highly decorative side to it.”