Passing two massive fragments of a wall, which are supposed to have formed part of a small temple of Jupiter, beside which numerous Christians suffered martyrdom, we come, at the fifth milestone, to a spot associated with one of those poetical legends which occur in the early annals of all nations, and whose hold upon the minds of men is itself an historic truth.  Here was the boundary between the territory of Rome and that of Alba.  Here was situated the entrenchment called the Cluilian Dyke, where Hannibal encamped, and where previously the Roman and Alban armies were drawn up in battle array, when it was agreed that the quarrel between them should be settled by three champions chosen from each side.  Every one knows the story of the Horatii and the Curiatii:  how these hapless brothers and cousins fought in sight of both armies with a bravery worthy of the stake; and how, at length, when two of the Roman heroes were slain, and all the Albans were wounded, the third Roman, who was unhurt, feigned to fly, and thus separating his enemies, who followed him as well as their failing strength would permit, easily despatched them one after the other, and thus gained the victory for the Roman cause.  This terrible tragedy, which terminated the independent existence of the Alban power, took place in the fields around here; and on the right-hand side of the road are three huge circular mounds, overgrown with long rich grass, planted with tall cypress and ilex trees, and surrounded at the foot with a wall of huge peperino blocks, which antiquarians have determined to be the tombs of the five slaughtered combatants—­the farther mound being that of the two Horatii, the second that of one of the Curiatii, and the third that of the other two Curiatii.  These tombs are situated exactly where we should have expected to find them from the description of Livy; and they are evidently of far older date than any of the neighbouring tombs of the imperial period.  Their form and construction carry us back in imagination to the earliest days of Rome, when Etruscan architecture was universally adopted as a model.  For more than twenty-five centuries the huge tent-like mounds have stood, so strikingly different in character from all the other sepulchral monuments of the Appian Way; preserved by the reverential care of successive generations.  The modern Romans have not been behind the ancient in the pride with which they have regarded these monuments.  They have planted them with the splendid cypress-trees which now add so much to their picturesqueness, and annually repair the ravages of time.  I climbed up the steep sides through the long slippery grass to the summits of two of the mounds, and had a grand view of the whole scene of the tragic story, bathed in the dim misty light which always broods over the melancholy Campagna like the spectral presence of the past.  The sunshine strove in vain to gild the dark shadows which the cypresses threw over the mound at my feet, and the lonely wind wailed wildly through their closely-huddled shivering branches around me.