The fountains in the Piazza del Popolo should not be considered as individual creations; they must be regarded as parts of an architectural composition which includes the piazza as a whole - its shape, dimensions, and location, and the buildings which surround it. This composition is the work of the distinguished Roman architect Giuseppe Valadier, whose life lay within the last thirty-eight years of the eighteenth century and the first three decades of the nineteenth. His bust stands in the place of honor on the Pincian; that is, it stands at the end of and facing the long, broad drive called the Passeggiata, which begins on the terrace before the Villa Medici and runs northward along the western crest of the Pincian Hill. Valadier had been papal architect under Pius VI and Pius VII, and he
had laid out for Napoleon the public gardens of the Pincian. Up to that time most of that land had belonged to the Augustinian monks whose convent stands below the hill, close to the Church of Santa Maria del Popolo. It has been their vineyard, and the story goes that it was while he was walking in this vineyard that Valadier got his first conception of what he might make out of the Piazza del Popolo.
Standing on the brow of the hill, from which is obtained the incomparable view of St. Peter's at sunset, Valadier looked down upon the Piazza del Popolo as Piranesi had engraved it in his time (1720-1778). A somewhat shapeless area of flat ground stretching in an indeterminate way westward from the base of the Pincian Hill, it seemed to be only the debouchment of the three great thoroughfares running into it from the heart of the city. The twin churches standing one on either side of the Corso, the centre thoroughfare, were the chief architectural features on the south side, while on the north side ran the city wall and the Church of St. Mary of the People. In the centre of this area stood the obelisk as it stands today, placed there by Sixtus V in 1589, and with a single fountain at its foot - a huge basin carved by Domenico Fontana out of one solid block of marble taken from the ruins of Aurelian's Temple of the Sun. The water supplying this fountain was the Acqua Trevi, the same which fills the fountains of the present day. Such was the Piazza del Popolo as Valadier's eyes beheld it, but at that point where the Aurelian wall is pierced by the Porta del Popolo (the old Flaminian Gate) he saw something else: He saw the end of the Flaminian Way - the great highroad leading directly from the north.