In the valley beneath St. Sebastian, on the left, is a large enclosure, covered with the greenest turf, and reminding one more, by its softness and compactness, of an English park than anything I had seen about Rome.  Here are the magnificent ruins of what was long known as the Circus of Caracalla; but later investigations have proved that the circus was erected in honour of Romulus, the son of the Emperor Maxentius, in the year 311.  It is the best preserved of all the ancient Roman circuses, and affords an excellent clue to the arrangements of such places for chariot races and the accommodation of the spectators.  The external walls run on unbroken for about a quarter of a mile.  In many places the vaults supporting the seats still remain.  The spina in the centre marking the course of the races, on either end of which stood the two Egyptian obelisks which now adorn the Piazza Navona and the Piazza del Popolo, though grass-grown, can be easily defined; and the towers flanking the extremities, where the judges sat, and the triumphal gate through which the victors passed, are almost entire.  It would not be difficult, with such aids to the imagination, to conjure up the splendid games that used to take place within that vast enclosure; the chariots of green, blue, white, and red driving furiously seven times round the course, the emperor and all his nobles sitting in the places of honour, looking on with enthusiasm, and the victor coming in at the goal, and the shouts and exclamations of the excited multitude.  On the elevated ground behind the circus is a fringe of olive-trees, with a line of feathery elms beyond; and rising over all, the purple background of the Sabine and Alban hills.  It is a lonely enough spot now; and the gentle hand of spring clothes the naked walls with a perfect garden of wild flowers, and softens with the greenest and tenderest turf the spots trodden by the feet of so many thousands.  In the immediate vicinity of the circus are extensive ruins, visible and prominent objects from the road, consisting of large fragments of walls and apses, dispersed among the vineyards and enclosures.

By far the best-known monument on the Appian Way is the Tomb of Caecilia Metella.  It is a conspicuous landmark in the wide waste, and catches the eye at a long distance from many points of view.  It is as familiar a feature in paintings of the Campagna almost as the Claudian Aqueduct.  This celebrity it owes to its immense size, its wonderful state of preservation, and above all to the genius of Lord Byron, who has made it the theme of some of the most elegant and touching stanzas in Childe Harold.  Nothing can be finer than the appearance of this circular tower in the afternoon, when the red level light of sunset, striking full upon it, brings out the rich warm glow of its yellow travertine stones in striking relief against the monotonous green of the Campagna.  It is built on a portion of rising ground caused by a current of lava which descended from the Alban volcano