Acqua Felice

The Acqua Felice is one of the aqueducts of Rome, completed in 1586 by Pope Sixtus V, whose birth name, which he never fully abandoned, was Felice Peretti. The first new aqueduct of early modern Rome, its source is at the springs at Pantano Borghese, off Via Casilina. Its length is fifteen miles, running underground for eight miles from its source, first in the channel of Aqua Alexandrina, then alternating on the arches of the Aqua Claudia and the Aqua Marcia for seven miles to its terminus at the Fontana dell'Acqua Felice on the Quirinal Hill, standing to one side of the Strada Pia, so as to form a piazza in this still new part of Rome.

Source: Wikipedia