Valadier lived in the period of the First Empire, when the shock of change and of contrast quickened even the most formal imagination. He came down from his “mount of vision” and designed the noble and finely proportioned piazza of the present day. He formed the vast and slovenly-shaped piece of ground into a stately ellipse, whose broadly curving ends, made of Roman brick and travertine, ornamented by sphinxes and allegorical figures, become the retaining walls of the terraced gardens at their rear, so that these long retaining walls seem coped by a line of glistening green foliage. On the side of the Pincian Hill the grass and trees of the Pincian Gardens rise in four tiers of terraces, high against the sky. Behind the retaining wall, opposite the Pincian, the tall cypresses screen the new city which stretches off toward the Tiber. A beautiful small semicircular basin, with a shell-like upper basin, stands in the centre of each of these curving ends. They might be called decorative keystones to recumbent arches. The water gushes through the retaining walls which form their background and falls between the convolutions of the shell in a fringe of steady, slender streams. It has been truly said that the eighteenth century did not die with the close of the year 1799. It lingered on through the first, and more than the first, decade of the century which followed. Valadier remained an eighteenth-century architect to the end of his life. This is most apparent in the Piazza del Popolo, his work of widest scope and freest fancy and the product of his most mature talent. Elegance, proportion, and formality are the qualities on which Valadier relies. His composition is simple, polished, and formal, and the note of affectation ingrained in the art of that period is given in the Egyptian character of some of the ornaments and accessories. This character was undoubtedly suggested by the obelisk, but it is a curious coincidence that many archæological remains of Egyptian origin have been discovered in this part of Rome. The allegorical groups placed behind the fountains represent on the side of the Pincian the god Mars in full armor, supported by the river-gods Anio and Tiber, each with his respective emblem, one of the emblems belonging to the Tiber being the figure of Mercury, the god of trade. On the side toward the river the group represents Neptune between two Tritons. These groups are by Valadier, and their mass of elaborate detail proves an admirable foil to the fountains beneath, which in their great simplicity are among the very loveliest in Rome. Small white marble sphinxes, said to be made out of blocks of Greek marble, found under the sea at the time that the bronze vase of Mithradates in the Palazzo dei Conservatori was discovered, mark the descending grades along the curving wall, and, as might be expected, statues of the four seasons adorn its four terminal piers.