summarize this text:
This great city of Tenochtitlan [Mexico] is situated in this salt lake, and from the main land to the denser parts of it, by whichever route one chooses to enter, the distance is two leagues. There are four avenues or entrances to the city, all of which are formed by artificial causeways, two spears' length in width. The city is as large as Seville or Cordova; its streets, I speak of the principal ones, are very wide and straight; some of these, and all the inferior ones, are half land and half water, and are navigated by canoes. All the streets at intervals have openings, through which the water flows, crossing from one street to another; and at these openings, some of which are very wide, there are also very wide bridges, composed of large pieces of timber, of great strength and well put together; on many of these bridges ten horses can go abreast. Foreseeing that if the inhabitants of this city should prove treacherous, they would possess great advantages from the manner in which the city is constructed, since by removing the bridges at the entrances, and abandoning the place, they could leave us to perish by famine without our being able to reach the main land--as soon as I had entered it, I made great haste to build four brigantines, which were soon finished, and were large enough to take ashore three hundred men and the horses, whenever it should become necessary.
This city has many public squares, in which are situated the markets and other places for buying and selling. There is one square twice as large as that of the city of Salamanca, surrounded by porticoes, where are daily assembled more than sixty thousand souls, engaged in buying, and selling; and where are found all kinds of merchandise that the world affords, embracing the necessaries of life, as for instance articles of food, as well as jewels of gold and silver, lead, brass, copper, tin, precious stones, bones, shells, snails, and feathers. There are also exposed for sale wrought and unwrought stone, bricks burnt and unburnt, timber hewn and unhewn, of different sorts. There is a street for game, where every variety of' birds found in the country are sold, as fowls, partridges, quails, wild ducks, fly-catchers, widgeons, turtle-doves, pigeons, reedbirds, parrots, sparrows, eagles, hawks, owls, and kestrels they sell likewise the skins of some birds of prey, with their feathers, head, beak, and claws. There are also sold rabbits, hares, deer, and little dogs, which are raised for eating and castrated. There is also an herb street, where may be obtained all sorts of roots and medicinal herbs that the country affords. There are apothecaries' shops, where prepared medicines, liquids, ointments, and plasters are sold; barbers' shops, where they wash and shave the head; and restaurateurs, that furnish food and drink at a certain price. There is also a class of men like those called in Castile porters, for carrying burdens. Wood and coals are seen in abundance, and braziers of earthenware for burning coals; mats of various kinds for beds, others of a lighter sort for seats, and for balls and bedrooms. There are all kinds of green vegetables, especially onions, leeks, garlic, watercresses, nasturtium, borage, sorrel, artichokes, and golden thistle; fruits also of numerous descriptions, amongst which are cherries and plums, similar to those in Spain; honey and wax from bees, and from the stalks of maize, which are as sweet as the sugar-cane; honey is also extracted from the plant called maguey, which is superior to sweet or new wine; from the same plant they extract sugar and wine, which they also sell. Different kinds of cotton thread of all colors in skeins are exposed for sale in one quarter of the market, which has the appearance of the silk-market at Granada, although the former is supplied more abundantly. Painters' colors, as numerous as can be found in Spain, and as fine shades; deerskins dressed and undressed, dyed different colors; earthenware of a large size and excellent quality; large and small jars, jugs, pots, bricks, and an endless variety of vessels, all made of fine clay, and all or most of them glazed and painted; maize, or Indian corn, in the grain and in the form of bread, preferred in the grain for its flavor to that of the other islands and terra-firma; pâtés of birds and fish; great quantities of fish, fresh, salt, cooked and uncooked ; the eggs of hens, geese, and of all the other birds I have mentioned, in great abundance, and cakes made of eggs; finally, every thing that can be found throughout the whole country is sold in the markets, comprising articles so numerous that to avoid prolixity and because their names are not retained in my memory, or are unknown to me, I shall not attempt to enumerate them. Every kind of merchandise is sold in a particular street or quarter assigned to it exclusively, and this is the best order is preserved. They sell every thing by number or measure; at least so far we have not observed them to sell any thing by weight. There is a building in the great square that is used as an audience house, where ten or twelve persons, who are magistrates, sit and decide all controversies that arise in the market, and order delinquents to be punished. In the same square there are other persons who go constantly about among the people observing what is sold, and the measures used in selling; and they have been seen to break measures that were not true.