is a two-book official report given to the emperor Nerva or Trajan on the state of the aqueducts of Rome, and was written by Julius Sextus Frontinus at the end of the 1st century AD. It is also known as or . It is the earliest official report of an investigation made by a distinguished citizen on Roman engineering works to have survived. Frontinus had been appointed Water Commissioner by the emperor Nerva in 95 AD.