They lie under your feet as a functional part of the paving, heavy and shiny. The Romans had them first, made of limestone at the time. When, from the 19th century onwards, sewer systems were installed in the cities that had grown rapidly in the course of industrialization, the cast-iron manhole cover - also known as gully cover - was born as an access opening into the urban underworld as we know it today.

This volume provides an insight into the fascinating graphic design language of these objects from all over the world. They offer an infinite variety of design, sometimes sober and standardized, sometimes playful or illustrative, and often reflecting the spirit of the country from which they originate and/or revealing interesting aspects of the respective location. The selected manhole covers are uniformly graphically stylized in black and white to maximize contrast and impact and to allow a focus on the essential.