despised people, surrounded and oppressed by enemies, had taken refuge on some islets in the western part of the saline lake of Mexico, and there by divine command they had founded the city which, under the title of Mexico Tenochtitlan, was to become the capital of Anáhuac. The first building was a temple of rushes, round which the settlement grew up, spreading rapidly over the islets, and on piles and filled ground. The city was enlarged and beautified by successive rulers, and when first beheld by the Spaniards it had attained its greatest extent—one it never again approached—and was reputed to be about twelve miles in circumference. This area embraced a large suburb of several villages and towns with independent names, containing in all sixty thousand houses, equivalent to a population of three hundred thousand.1
Four great avenues, paved with hard cement, ran crosswise from the cardinal points, and divided the city into as many quarters, which were again subdivided into wards.2
Three of the avenues were connected in a straight line, or nearly so, with the main land by means of smooth causeways, constructed of piles filled up with rubble and débris. The shortest of these was the western, leading to Tlacopan, half a league distant, and bordered all the way with houses. They were wide enough for ten horsemen to ride abreast, and were provided at intervals with bridges for the free flow of water3 and of traffic. Near their junction with the city were drawbridges, and breastworks for defence. A fourth causeway, from the Chapultepec summer palace, served to support the aqueduct which
carried water from the mountain spring in that vicinity.
Round the southern part of the city stretched a semicircular levee, three leagues in length and thirty feet in breadth, which had been constructed in the middle of the preceding century to protect the place from the torrents which after heavy rains came rushing from the fresh-water lakes