For the Romans, the dome of Saints Peter’s Basilica is, confidentially, ‘er cuppolone’, meaning the huge dome. Similarly, the beautiful 17th-century fountain of Aqua Paola, on the top of the Janiculum, is known as ‘er fontanone’, the huge fountain. Its construction was commissioned by Pope Paul V, intending to solve the long-standing problem of water supply in the districts of Trastevere, Borgo and Vaticano. The Pope commissioned the project to the architect Carlo Fontana, who, inspired by the Aqua Felice, which he himself designed in 1587, had it built between 1611 and 1612. Much larger than its ‘sister’, the fountain somehow copies its structure, the upper half of which is occupied by rectangular windows that allowed a glimpse of the botanical garden which, at the time, opened behind the fountain. The upper half of the monument is occupied by a long inscription – bearing witness to the construction of the aqueduct – surmounted by a huge papal coat of arms, supported by two angels.