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.

Courtesy of Wired Magazine.