Raoul de Presles gives some interesting details about the marsh which Labienus, on making his advance against Paris, was unable to cross. Some identify it with the Marshes of the Temple, which formed, on the north of Paris, a continuous semicircle; but Raoul de Presles seems to hold that the marsh which stopped the advance of Labienus protected Lutetia itself: that Lutetia of the Island which sprang from the mud as Venus sprang from the sea. The city of Lutetia was at that time so strong, so entirely shut in by water, that Julius Cæsar himself speaks of the difficulty of reaching it. "But since then," says Raoul de Presles, "there has been much solidification through gravel, sand, and all kinds of rubbish being cast into it." After the victory of Labienus, Lutetia, which the conqueror had destroyed, was quickly re-built; and it was then governed as a Roman town. This, however, was in Cæsar's time; and the first description of Lutetia as a city was given by Strabo some fifty years later. Thus it may safely be said that of the original Lutetia nothing whatever is known. It is certain, nevertheless, that in the new Lutetia, built by the Romans, the most important edifices stood at the western end of the island, including a palace, on whose site was afterwards to be erected the Palace of the French Kings; while at the eastern end the most striking object was a Temple to Jupiter, in due time to be replaced by the Cathedral of Notre-Dame. As early as the fourth century Lutetia found favour in the eyes of illustrious visitors; and the Emperor Julian, known as the "Apostate," when, after defeating seven German kings near Strasburg, he retired to Lutetia for winter quarters, spoke of it, then and for ever afterwards, as his "dear Lutetia." "Lutetia lætitia!"--Paris is my joy!--he might, with a certain modern writer, have exclaimed. Julian is not the only man who, going to Paris for a few months, has stayed there several years; and Julian's winter quarters of the year 355 so much pleased him that he remained in them until 360. Encouraged, no doubt, by what Julian, in his enthusiasm, told them about the already attractive capital of Gaul, a whole series of Roman emperors visited the city, including Valentinian I., Valentinian II., and Gratian, who left Paris in 379, never to return. From this date Paris ceased practically to form part of the Roman Empire. More than a century before (in 245) St. Denis had undergone martyrdom on the banks of the Seine, walking about after decapitation with his head under his arm. This strange tradition had probably its origin in a picture by some simple-minded painter, who had represented St. Denis carrying his own head like a parcel, because he could think of no more ingenious way of indicating the fate that had befallen the first apostle of Christianity in Gaul; just as St. Bartholomew has often been painted with his skin hanging across his arm like a loose overcoat.