Owing to the breadth and size of the stream, and the violence of the current at the time of the inundation, the building of a permanent bridge was no easy task. Strabo puts the breadth of the Euphrates at Babylon at 600 feet, Xenophon who saw the river some miles above Babylon puts it at twice that breadth.[717] Diodorus has already told us that the bridge was five stades, _i.e._ 3000 feet, long. This statement may be exaggerated, yet owing to the heavy flood at the time of the inundation, however this might be moderated by the basin at Sippara, the bridge must have been raised so high, the buttresses and shore walls must have been thrown so far back, that a considerably increased body of water could pass down without undermining the casings and the shore walls. That the new basin at Sippara was used in order to facilitate the building of the bridge, and erection of the shore walls, in order to reduce as much as possible the amount of water in the stream while the building was going on, as Herodotus tells us, is a statement we have no reason to contest. In his time the bridge was still standing: the companions of Alexander make no mention of it. Nebuchadnezzar's buildings at Babylon were intended in the first instance for the protection of the city. Sennacherib and Assurbanipal had taken Babylon; such a misfortune was never to befall the city again. Nineveh and Chalah had been situated on one side only of the Tigris: Babylon must be situated on both sides of the Euphrates. The city became stronger by being situated on both sides of the river. The investment would be a matter of difficulty, for the investing army had to be divided, and these halves were separated by the Euphrates, so that they could with difficulty keep up communications, still less could they render mutual assistance. The investment would become more difficult still if as wide a circuit as possible were given to the city wall. It was not the multitude of inhabitants that required a wall of nearly 40 miles in length--there is here no ground for attributing to the city of Babylon a much larger population than that of Nineveh, or assuming it to be more than 500,000--the object was to make a blockade difficult or impossible for an enemy. An outer wall of 40 miles is scarcely greater in extent than the outer wall of Paris, which was built in the fourth century of our era, and what the states of the most ancient civilisation on the Nile, the Euphrates, and Tigris could do in the way of vast buildings, is shown to us in numerous examples, and remains on an astonishing scale. By thus extending the city walls of Babylon strips of arable and pasture land were obtained, which supplemented the stores of the city, and could support the cattle required in a time of siege; an open space was gained for the population of the land, who would fly into the walls of Babylon at the approach of an enemy. Besides, the walls of Babylon must be in a position to receive the Babylonian army in the