The striking technology of the Aztec capital is vividly portrayed in the map allegedly produced on Cortes’s orders and subsequently printed along with his letter to Charles V describing the city (see Figure 7.4). It shows the causeways which connected the island city to the mainland and which continued as streets intersecting at right angles at the central square where the main pyramidal temple stood. Clearly visible along the causeways are the bridges which could be removed when enemy attack threatened. And at one extremity is depicted the city’s defence from floods: a barrage of wooden piles and containers filled with rubble and clay. But the map could not display two other remarkable technological achievements. The drinking-water brought by earthen aqueducts from a distant spring was distributed not only by ubiquitous canoes but also by a network of pipes to supply the temples, Montezuma’s palace and chieftains’ houses. And an ingenious system of intensive aqueous horticulture provided the basis for urban subsistence, as well as a beautiful green appearance. The aim was to create farmland over the lake and anchored to the bottom. Fertile soil from the mainland was brought by canoe to the lake, where it was deposited in shallow water on a trellis of reeds, secured by wooden posts to the lake bed. The earth was dropped until it formed a mound rising nearly a metre above the surface of the water. Willow trees, planted at the edge of the sunken trellis, took
root and consolidated the terrain. Even during drought, the lagoon kept the earth mounds moist, a highly fertile medium for maize, fruit and vegetables. These artificial gardens, called chinampas, covered an estimated area of 128 square kilometres around the city and, on recent calculations, could have produced enough food for a population of 100,000 (Armillas, 1971; Musset, 1991a, p.236). Other food came in the form of the abundant fowl attracted to the lake.