Rome's aqueduct system eventually comprised eleven principal aqueducts with a total length of approximately 800 kilometers, supplying between 500,000 and 1,000,000 cubic meters of water daily to a city of more than a million inhabitants. The complete system, from mountain-spring capture to urban distribution and sewerage (Cloaca Maxima), operated entirely by gravity through a carefully calculated gradient. The engineer Sextus Julius Frontinus, curator aquarum from 97 AD, describes the system in De aquaeductu Urbis Romae with technical detail sufficient for its reconstruction. Rome's per-capita water supply (estimated at 500-1,000 liters per inhabitant per day) was not matched by any European city until London in the 19th century. The fall of the Roman Empire led to the system's abandonment and the collapse of the water supply; medieval Europe depended for centuries on wells and rivers. The historical canon of hydraulic engineering often presents Roman aqueducts as heirs to the Greek tradition, when in fact the scale, duration, and systemic integration of the Roman system has no documented precedent.