“The sewer is the conscience of the city,” Victor Hugo famously wrote in “Les Miserables.” In Cairo, architect Salma Nassar used the photos of sewer covers to shed a light on the city’s sanitation, and strangely enough, political symbols.

The “Cairo Sewer Covers Exhibition,” which took place March 20-28 at the Cairopolitan art gallery, featured photos of various forms of sewer covers that date back to 1915. Some covers were green portraying three crescents with three stars, symbolizing the unity of Egypt, Sudan and Nubia in the ancient Egyptian flag. The flag's main color was green, indicating the fertility of the Nile Delta.

Another icon, which appeared on the sewer covers until the revolution of July 1952, was a crescent with a star. From the 1950s onward, an eagle appeared on the sewer covers, symbolizing the Egyptian Republic. This symbol is still used today. The logos of the state companies that made these covers also appeared on the sewer covers.

“Hugo said that 'the sewer is the conscience of the city.' So we launched this exhibition to explore the history of the capital Cairo through its sewer covers,” Nassar — whose passion of urban architecture and urban development led her to years of research, documentation and taking photos of covers — said at the opening of the exhibition.