Remains of the ancient wall of fortification of the capital have also been brought to light, at various localities and at different dates. The excavations in the Parvis-Notre-Dame in 1847 discovered a section of the Roman wall twenty-six mètres in length, as well as the substructure of the porch and the front portion of the nave of the original basilica, constructed by Childebert and dedicated to the Virgin. These latter foundations, some thirty-two mètres in front of the present cathedral, demonstrate by their position, and by the probable width of the primitive edifice in proportion to its length, that they were constructed to the west and inside of the enclosing wall of the city, a portion of which had been found under the choir of the cathedral. The basilica constructed by the son of Clovis probably rose on the site of the altars consecrated to the Roman or Gaulish gods, Jupiter, Vulcan, Esus, and others, and which, before the construction of the city wall, were visible from all sides. The enclosing wall, on the contrary, fenced in the basilica, since it was necessary to protect this part of the city, as well as all others. The somewhat unimposing aspect of Notre-Dame, which was founded in 1163, may be ascribed in part to the raising of the level of all the surrounding soil, for, as the histories tell us, so late as 1748, it was reached only by ascending a flight of thirteen steps, whereas now it is on the ordinary street-level. This wall of defence was not commenced till about 406, when the barbarians began to invade Gaul, and was apparently constructed in great haste, if we may judge by the manner in which materials were borrowed from surrounding buildings of all kinds. It is described as being something over three and a half mètres in thickness at its base, which was constructed in rough stone, frequently of small size, and sloping to a height of two mètres. On this was erected a wall of dressed stones, each successive layer set back, like a step, so that at the top it was only some two mètres in width. It might be thought that this manner of building offered considerable facilities to an escalading enemy.