Last of all, the great temple of the Sun, with its vast portico, and the Mithræum at the other end, and when the walls of Aurelian are built, and when ruin comes upon Rome from the north, the Campus Martius is still almost an open stretch of dusty earth on which soldiers have learned their trade through a thousand years of hard training. Not till the poor days when the waterless, ruined city sends its people down from the heights to drink of the muddy stream does Campo Marzo become a town, and then, around the castle-tomb of the Colonna and the castle-theatre of the Orsini the wretched houses begin to rise here and there, thickening to a low, dark forest of miserable dwellings threaded through and through, up and down and crosswise, by narrow and crooked streets, out of which by degrees the lofty churches and palaces of the later age are to spring up. From a training ground it has become a fighting ground, a labyrinth of often barricaded ways and lanes, deeper and darker towards the water-gates cut in the wall that runs along the Tiber, from Porta del Popolo nearly to the island of Saint Bartholomew, and almost all that is left of Rome is crowded and huddled into the narrow pen overshadowed and dominated here and there by black fortresses and brown brick towers. The man who then might have looked down from the Pincian hill would have seen that sight; houses little better than those of the poorest mountain village in the Southern Italy of today, black with smoke, black with dirt, blacker with patches made by shadowy windows that had no glass. A silent town, too, surly and defensive; now and then the call of the water-carrier disturbs the stillness, more rarely, the cry of a wandering peddler; and sometimes a distant sound of hoofs, a far clash of iron and steel, and the echoing yell of furious fighting men--'Orsini!' 'Colonna!'--the long-drawn syllables coming up distinct through the evening air to the garden where Messalina died, while the sun sets red behind the spire of old Saint Peter's across the river, and gilds the huge girth of dark Sant' Angelo to a rusty red, like battered iron bathed in blood.