Babylon, says Herodotus, was planted in an open plain and formed an exact square of great size, 120 stades (that is, nearly 14 miles) each way; the whole circuit was 480 stades, about 55 miles.  It was girt with immense brick walls, 340 ft. high and nearly 90 ft. thick, and a broad deep moat full of water, and was entered through 100 gates; presumably we are intended to think of these gates as arranged symmetrically, 25 in each side.  From corner to corner the city was cut diagonally by the Euphrates, which thus halved it into two roughly equal triangles, and the river banks were fortified by brick defences—­less formidable than the main outer walls—­which ran along them from end to end of the city.  There was, too, an inner wall on the landward side.  The streets were also remarkable: 

’The city itself (he says) is full of houses, three or four storeys high, and has been laid out with its streets straight, notably those which run at right angles, that is, those which lead to the river.  Each road runs to a small gate in the brick river-wall:  there are as many gates as lanes.’[9]

[9] Hdt. i. 180 [Greek:  To de astu auto, eon pleres ohikieon triorhofon te kai tetrorofon, katatetmetai tas hodous itheas, tas te aggas kai tas epikarsias, tas epi ton potamon echousas].  Apparently [Greek:  epikarsias] means, as Stein says, those at right angles to the general course of the river, but this nearly = at right angles to the other roads.  The course of the river appears to have been straighter then than it is now.

In each part of the city (that is, on either bank of the Euphrates) were specially large buildings, in one part the royal palaces, in the other the temple of Zeus Belos, bronze-gated, square in outline, 400 yards in breadth and length.

So far, in brief, Herodotus.  Clearly his words suggest town-planning.  The streets that ran straight and the others that ran at right angles are significant enough, even though we may doubt exactly what is meant by these other streets and what they met or cut at right angles.  But his account cannot be accepted as it stands.  Whatever he saw and whatever his accuracy of observation and memory, not all of his story can be true.  His Babylon covers nearly 200 square miles; its walls are over 50 miles long and 30 yds. thick and all but 120 yds. high; its gates are a mile and a half apart.  The area of London to-day is no more than 130 square miles, and the topmost point of St. Paul’s is barely 130 yds. high.  Nanking is the largest city-site in China and its walls are the work of an Empire greater than Babylon; but they measure less than 24 miles in circuit, and they are or were little more than 30 ft. thick and 70 ft. high.[10] Moreover, Herodotus’s account of the walls has to be set beside a statement which he makes elsewhere, that they had been razed by Darius sixty or seventy years before his visit.[11] The destruction can hardly have been complete.  But in any case Herodotus can only have seen fragments, easily misinterpreted, easily explained by local ciceroni as relics of something quite unlike the facts.