 Their courses are by now highly artificial, the result of land and water management projects undertaken over many centuries, since they are recorded at least as early as the time of Theodoric the Great (6th century) and have continued down to our own time with the construction of dams and works to regularize the seasonal waters of the Marroggia that had been subject to frequent torrential overflows with sudden and disastrous results.The most important of the year-round watercourses is the Clitunno River, celebrated in antiquity as the Clitumnus, whose deified waters were reputed to have miraculous properties and which have been lauded in prose and verse by Pliny the Younger, Propertius, Claudian, Addison, Byron and Carducci.Trevi borders the following municipalities