This gradual consolidation of the land which was reclaimed slowly from the Seine must have gone on from the time when the Roman walls stopped at the Rue aux Ours on one side, and at the Rue Saint Denis on the other. Their northern boundary was very slightly farther than the Rue aux Fosses Louis VIII. The Rue Jeanne d'Arc runs just outside them to the west, and the stream of Robec forms their natural boundary to the east, flowing into the _Mala Palus_ that has left its name in the Rue Malpalu which leads from the west front of St. Maclou towards the Seine. Robec himself is well-nigh hidden now, though once his southern turn formed one of the defences of the town. Now he gropes underground his way into the Seine, and even when his waters can be traced, in the Rue Eau de Robec, their muddy waves were almost better hidden. There is a striking likeness to all this in the early days of the history of London. Apart from all legends of the Troy Novant, of Lud and Lear and that King Lucius who sanctified Cornhill, legends which have their counterpart in all the old histories of Rouen, there are almost as few relics of the fortified barrack on the Thames, or of the more pretentious "Augusta" which followed, as there are of Roman Rouen. The same mud flats along the river bank remained until, in 982, after the first great fire, Cnut made a canal for his boats round Southwark. Into the marsh fell the Fleet river, just as Robec into Mala Palus; the English stream like the French one, formed the first natural line of defence on that side; and both are now little better than built-in sewers, one flowing into Thames at Blackfriars Bridge, the other through its smaller tunnel into Seine near the Pont de Pierre Corneille.