The Puebloans, ingenious farmers of the high desert, were master builders. Their earliest structures, half-buried pithouses, evolved into above-ground pueblos by 1000 CE. Soon the Puebloans were building many of their villages on mesa tops, perhaps with defense in mind or perhaps simply to be high above the plain.
Atsinna Pueblo, the largest of the pueblos atop El Morro, dates from about 1275. Its builders made use of what they had around them: flat sedimentary rock easily cut up as slabs they could pile one on top of another and cement with clay and pebbles. The pueblo was about 200 by 300 feet. The cuesta top housed between 500 and 600 people. Interconnected rooms - 355 have been counted -- surrounded an open courtyard. Square and circular ceremonial rooms - underground chambers that recall the pithouse era - were spaces for informal gatherings as well as their religious ceremonies.
Corn and other crops were grown in irrigated fields, down on the plain; the surplus was stored in well-sealed rooms in the pueblo against times of need. The grinding bins and firepits remain today.
Cisterns on top of the mesa collected rainwater. The pool at its base was often used too, as hand-and-toe steps on the cliff face attest. An alternate trail for the residents may have followed the one that is still in use today.