In Ancient Rome, engineering ingenuity extended beneath the city streets with the construction of the Cloaca Maxima, one of the earliest and most remarkable sewer systems in history. Originally built in the 6th century BCE, this massive drainage system was designed to channel stormwater and wastewater out of the bustling city and into the Tiber River.

Far from a modern treatment plant, the Cloaca Maxima’s purpose was strictly utilitarian: to prevent flooding and improve sanitation in a rapidly growing metropolis. Its impressive network of tunnels and conduits was constructed using stone and concrete, materials that have allowed parts of the system to remain functional even today—over 2,500 years later.

While it didn’t treat wastewater like contemporary treatment plants, the Cloaca Maxima set a precedent for urban sanitation systems, influencing infrastructure development in cities around the world. It stands as a testament to Roman engineering, a reminder that even ancient civilizations understood the importance of managing what lies beneath.