So densely crowded were the historical buildings and remarkable sites in that part of the Forum which lay immediately behind the Capitol, that it is almost impossible now to identify their position or remains. This spot forms the great battle-ground of the antiquaries, whose conclusions in many instances are mere guess-work. Below the medieval tower of the Capitol is a wide space paved with fragments of coloured marbles, and with indications of the ground-plan of a building. This is supposed to mark the site of the Temple of Concord, erected by the great general Camillus, after the expulsion of the Gauls, to perpetuate the concord between the plebeians and patricians on the vexed question of the election of consuls. It was placed beside the old meeting-place of the privileged families. From the charred state of some of its sculptures discovered on the spot, it is supposed to have been destroyed by fire. It was restored and enlarged a hundred and twenty years before Christ by the Consul Opimius immediately after the murder of Caius Gracchus. To the classical student it is specially interesting as the place where Cicero convoked the senate after the discovery of the Catiline conspiracy, for the purpose of fixing the punishment due to one of the greatest of crimes. Among the senators present on that memorable occasion were men of the highest political and philosophical renown, including Cæsar, Cato, and Cicero. They came to the conclusion that there was no such thing as retribution beyond the grave, no future state of consciousness, no immortality of the soul; consequently death was considered too mild a punishment for the impious treason of the conspirators; and a penalty, which should keep alive instead of extinguishing suffering, was advocated. We learn from this extraordinary argument, as Merivale well says, how utter was the religious scepticism among the brightest intellects of Rome only thirty-seven years before the coming of Christ. The very name of the temple itself, dedicated not to a divine being as in a more pious age, but to a mere political abstraction, a mere symbol of a compact effected between two discordant parties in the state, indicated how greatly the Romans had declined from their primitive faith.

But the most conspicuous of the ancient remains in this quarter, and the first to attract the notice of every visitor, is the Ionic portico of eight columns, called at first the Temple of Jupiter, and then of Vespasian, but now definitely determined to be the Temple of Saturn, for it is closely connected with the Ærarium, and the Ærarium is said by several ancient authors to have led into the podium of the temple by a doorway in its wall still visible. This temple is supposed to be of very early origin, and to have marked the site of an ancient Sabine altar to the oldest of the gods of Italy long before the arrival of the Romans. It was nearly entire so late as the fifteenth century; but its cella was ruthlessly destroyed shortly afterwards, and its marble ornaments used for making lime. The present group of pillars was so clumsily restored by the French at the beginning of this century that they are seen to differ from each other in diameter, and the frieze is composed of fragments that do not harmonise.

But the most remarkable monument of antiquity in this part is the marble triumphal Arch of Septimius Severus, which stands in front of the ruins of the Temple of Concord. It invaded the site of the republican Græcostasis, where foreign ambassadors waited for an audience of the senate, and occupied part of the area of the Comitium, whose original character was thereby destroyed; for it was erected at a time when men ceased to care for the venerable associations connected with the early history of their city. One gazes upon this monument of Roman power and pride with deep respect, for it has stood nearly seventeen centuries; and though rusty and sorely battered, and its sculptures much mutilated, it is still one of the most solid and perfect relics of imperial times. It was raised to commemorate the wars of Septimius Severus in Parthia and Arabia; and represents among its carvings the goddess Rome receiving the homage of the Eastern nations. It exhibits on its panels many scenes connected with his campaigns, the memory of which no humane man would have liked to perpetuate. On the upper part of the Arch is a large inscription in honour of the emperor and his two sons, Caracalla and Geta. The name of Geta, however, was afterwards erased by his brother when he had murdered him, and other words substituted. Marks of the erasure may still be seen perfectly distinct after all these centuries, and vividly recall the terrible associations of the incident. The dislike which Caracalla and Geta had for each other was so virulent that their father took them both with him to Britain, in order that they might forget their mutual animosity while engaged in active warfare. Septimius Severus died during this campaign at York, and his sons returned to Rome to work out soon after the domestic tragedy of which this Arch reminds us. On the top of the Arch there was originally a bronze group of a chariot and four horses, with the emperor and his sons driving it. But this was removed at an early date; and in the middle ages the summit of the Arch supported the campanile of the church of St. Sergius and Bacchus that was built up against its sides. A little to the left, the road passing under the Arch joins the Clivus Capitolinus which wound through the Forum, and led up to the great Temple of Jupiter on the Capitol. The pavement of this ancient road, which still exists, is formed of broad hexagonal slabs of lava, and is as smooth and as finely jointed at this day as when the triumphal processions of the victorious Roman generals used to pass over it.