The monumental Fontana dell' Acqua Paola (1608-12), which is also known simply as Il Fontanone (the big fountain), is situated on the Janiculum hill. The fountain was commissioned by Pope Paul V (r. 1605-21) and designed by the aptly-named Giovanni Fontana (1540-1614) and Flaminio Ponzio (1560-1613).
The Fontanone, which was the first major fountain to be erected on the left bank of the River Tiber, was fed by the Aqua Trajana, an ancient aqueduct built by the emperor Trajan (r. 98-117). The aqueduct was restored by Pope Paul V and renamed the Acqua Paola.
The façade of the fountain is adorned with six granite columns, which support an architrave bearing an inscription, 'In the year of our Lord, 1612, and the seventh year of the pontificate’.
The longer inscription reads, 'Paul the Fifth, Pontifex Maximus, collected this water, drawn from the purest of springs in the neighbourhood of Bracciano, and brought it for 35 miles from its source over the ancient channel of the Aqua Aliestina, which he restored, and over new ones, which he added.'
The Fontana dell' Acqua Paola is surmounted by the coat of arms of Paul V's family, the Borghese.