The grand staircase, "_La Cordonnata_," was opened in its present form on the occasion of the entry of Charles V., in 1536.[38] At its foot are two lions of Egyptian porphyry, which were removed hither from the Church of S. Stefano in Cacco, by Pius IV. It was down the staircase which originally existed on this site, that Rienzi the tribune fled in his last moments, and close to the spot where the left-hand lion stands, that he fell, covered with wounds, his wife witnessing his death from a window of the burning palace above. A small space between the two staircases has lately been transformed into a garden, through which access may be obtained to four vaulted brick chambers, remnants of the substructions of the temple of Jupiter Capitolinus. A living wolf is kept here in commemoration of the nurse of Romulus and Remus. At the head of the stairs are colossal statues of the twin heroes, Castor and Pollux (brought hither from the Ghetto), commemorating the victory of the Lake Regillus, after which they rode before the army to Rome, to announce the joyful news, watered their horses at the Aqua Argentina, and then passed away from the gaze of the multitude into celestial spheres. Beyond these, on either side, are two trophies of imperial times discovered in the ruin on the Esquiline, misnamed the Trophies of Marius. Next come statues of Constantine the Great and his son Constantine II., from their baths on the Quirinal. The two ends of the parapet are occupied by ancient Milliaria, being the first and seventh milestones of the Appian Way. The first milestone was found in _situ_, and showed that the miles counted from the gates of Rome, and not, as was formerly supposed, from the Milliarium Aureum, at the foot of the Capitol.