We are indebted to this inconsiderable little monument--stated in the inscription to have been raised by the silversmiths and cattle-dealers to the imperial family of Septimius Severus--for the important information that the Forum Boarium, mentioned in the legends of the foundation of Rome, was situated on this spot. The sculptures with which the arch is ornamented are much defaced, and hidden from view on one side by the Church of S. Giorgio. Those in the interior represent sacrifices offered by the emperor and his sons. On one of the side piers is the figure of Hercules, evidently having reference to this locality, which was consecrated to him, and in the neighbourhood of which he had actually erected the Ara Maxima. At the back is a representation of a ploughman with a yoke of oxen, also in allusion to the myths, the different threads of which all unite at this point. On the inside _right_ are the effigies of Septimius and his wife Julia; and opposite them were Caracalla and Geta, but the latter has been cut out, leaving only his brother. On the pilasters, the capitals of which are Roman, we discover among various field-badges the portraits of the emperor, his wife, and one of his sons; that of Geta having been obliterated after his murder, by the order of Caracalla. It is rather a misnomer to call this an arch, as it has a flat top. _Adjoining is the_ CHURCH OF S. GIORGIO IN VELABRO, founded in the fourth century. The architrave above the portico (of the thirteenth century) is where Rienzi affixed his proclamation announcing, "In a short time the Romans will return to their ancient good estate." It is seldom opened, except on its festival, January 20th. The aisles are formed by sixteen different columns, no doubt the plunder of some other building. It is dedicated to the patron saint of England, a piece of whose banner is preserved beneath the altar. _Proceeding down the low brick archway opposite brings us to_ THE CLOACA MAXIMA,