A still more important architectural feature of the ancient city was the great aqueduct which supplied the baths of the palace on the river, its fountains and those of the populous quarter around it. The waters of three or four small streams to the south of the capital were united and conveyed in a channel, lined with cement, 19,100 mètres in length, which traversed the slopes of the hills on the eastern side of the Bièvre, and remains of which have been found at various points. To cross the valley and the stream, an aqueduct was constructed on arches at the locality which took the name of Arcueil, and where some of the masonry is still preserved in modern construction, "this aqueduct being some four hundred mètres long and fifty (?) high." It is computed that a supply of twenty-four cubic mètres of water was furnished every twenty-four hours. Remains of other and smaller aqueducts have been discovered at various points in the city. At Passy, surrounding the present Trocadéro, there were springs of mineral waters, which were conveyed to the city by terra-cotta pipes, passing along the banks of the Seine. In 1781, in the gardens of the Palais-Royal, were discovered the remains of great basins which are supposed to have been the piscines of the hygienic baths. Remains of Roman aqueducts have been found at various other localities in France, at Nîmes, at Lyons, at Metz, etc., and that over the Gard is still standing in part. Among the bridges constructed by the Gauls, Cæsar mentions that of Melun on the Seine; one on the Allier, near Vichy; that of Genabum (Orléans), and that of Lutetia, over the larger arm of the Seine, on the site of the present Pont Notre-Dame. Of that over the Allier and of the Parisian one, some of the ancient piles have been found in the bed of the rivers.