waTeR and The sacRed ciTy • 39causeway of Tepeyacac, looping outward toward the east
to run along the city’s littoral and then joining with the
causeway of Ixtapalapa.
The creation of this shorter dike, called the dike of
Ahuitzotl, after its patron, most likely served to protect
the city from freshwater, that is, floodwaters coming from
the Laguna of Mexico. 45 Had Ahuitzotl faced saltwater
inundations from Lake Tetzcoco, the solution would have
been to raise the level of the Nezahualcoyotl dike. Instead,
it seems as though within this (now) freshwater system,
too much water flowing in from the higher, southern lakes
of Chalco and Xochimilco washed into the Laguna of
Mexico, which now had a restricted capacity because of
the bulwark of the dike of Nezahualcoyotl. Thus, these
freshwaters flooded eastern Tenochtitlan, no doubt enter-
ing the city via back-flooding of the very east–west canals
that were supposed to guide water out from the urban core.
Construction of this second dike probably began in 1500, or
as early as the fall of 1499, when the dry season began and
the waters receded. It achieved two goals. First, it created a
more secure system to maintain lake levels in the Laguna of
Mexico, because of the double band of protection between
it and Lake Tetzcoco. The inner band was created by the
causeway of Tepeyacac, the dike of Ahuitzotl, and the
causeway of Ixtapalapa, and the outer band by the dike
of Nezahualcoyotl. The distance between these retaining
roads and dikes was barely a third of a mile at its narrowest
point, right off the shore of Tenochtitlan (around where
the Archivo General de la Nación now sits). Farther to the
south, the distance between the Ixtapalapa causeway and
the dike of Nezahualcoyotl was about one and one-fourth
miles (figure 2.7). The second function of the causeways
and dikes was to create more arable land within Tenoch-
titlan itself. Protected by the dike of Ahuitzotl, the eastern
edge of the city was safely reclaimed from threats from
the salty waters of Lake Tetzcoco; this pattern of building
outward into the lake from terra firma has a long history,
as archeology and the present-day expanse of Mexico City
demonstrate. 46
Lived sPaces in The maP
of sanTa cRuz
While the tlatoque (supreme leaders) of Tenochtitlan were
quick to connect themselves to works of successful aquatic
engineering, as reflected in later histories, many residents
of the city would have understood the waterworks close
up, in their experiences of building and maintaining them,
since the process would have drawn on thousands of men
and women to haul tree trunks, break stones, dig postholes,
and make tortillas for workers. The exploratory archeology
by Carballal Staedtler and Flores Hernández could not
include excavations along this long dike of Nezahualcoyotl
to determine how it was constructed, but they suggested
a comparison to the causeway of Tepeyacac, along which
they did excavate. They found that this causeway was con-
structed by using large tree trunks as pylons to secure the
sides of the causeway by forming retaining walls, which
were then filled in with stone; Torquemada also mentions
the great estacas, “pylons,” that were brought from the lake-
side cities as well as the large and heavy stones used in the
dike’s construction. 47 If we look again at the 1524 map of
the city from Cortés’s Second Letter, we can see that its art-
ist has represented the dike as a horizontal fence set below
the city within the lake, and it looks as if it were made of
woven wicker (see figure 1.11). This rendering may have as
its source an earlier drawing of the dike that showed these
vertical wooden pylons woven with horizontal saplings to
hold the fill.
By the eighteenth century, when the lake waters had
receded, the ruins of this dike appear in a 1768 map show-
ing fields to the west of the city. At that point, few remains
were left of the wooden pilings, and the dike was little more
than a long wall of piled stone. 48 In a nineteenth-century
record, also cited by Carballal Staedtler and Flores Hernán-
dez, the ruined dike, after centuries of erosion and pillaging
for stone, still measured between twenty-six and thirty-
three feet thick and over three feet high, which points to
the initial extent of this protective earthwork, which they
suggest was once twenty-three feet thick. 49 The amount of
labor required to construct these dikes was enormous, even
greater than the mobilization for warfare; in the 1555–1556
reconstruction of the inner dike, the shorter of the two,
historian Charles Gibson reports that while the viceroy
summoned six thousand indigenous laborers, another,
unofficial account calculated that two million men were
employed over several months for the same work. 50
If residents of the city knew these dikes intimately as
products of their labor, they also knew the happy effect
of these parallel barriers, which was registered in one of
the most important representations of the city’s space,
created some years after the Conquest. The magnificent
Map of Santa Cruz shows a bird’s-eye view of the entire
valley oriented to the west at top, with the island city