In ancient times, aqueducts carried spring water from distant sources to central Rome. As the Empire decayed, so, too, did these ambitious public works. When Rome experienced a Renaissance--not to mention a population boom--in the modern age, popes took cues from the emperors before them and repaired ancient water channels, once again guaranteeing an abundance of water for the city center.
To celebrate their grand projects, Popes built massive public fountains like the Fontana dell'Acqua Paola on the Janiculum Hill. Dubbed "er fontanone" (the very big fountain), the 17th century structure was commissioned by Pope Paul V Borghese to celebrate the repair of Trajan's aqueduct that tapped a spring near Lake Bracciano north of Rome. Today, the Fontanone is the backdrop for summer performances and it looks out across the city skyline. To reach the monument and its adjacent scenic overlook, follow the Via Garibaldi uphill from Trastevere.