The cultural flowering of the Chacoan people began in the mid-800s and lasted over three hundred years. We can see it clearly in the grand scale of the architecture. Using masonry techniques unique for their time, they constructed massive stone buildings ("great houses') of multiple stories containing hundreds of rooms much larger than any they had previously built. The buildings were planned from the start, in contrast to the usual practice of adding rooms to existing structures as needed. Construction on some of these buildings spanned decades and even centuries. Although each is unique, all great houses share architectural features that make them recognizable as "Chacoan."

During the middle and late 800s, the great houses of Pueblo Bonito, Una Vida, and Pehasco Blanco were constructed, followed by Hungo Pavi, Chetro Keti, Pueblo Alto, and others. These structures were often oriented to solar, lunar, and cardinal directions. Lines of site between the great houses allowed communication. Sophisticated astronomical markers, communication features, water control devices, and formal earthen mounds surrounded them. The buildings were placed within a landscape surrounded by sacred mountains, mesas, and shrines that still have deep spiritual meaning for American Indian descendants.

By 1050, Chaco was well on the way to becoming the political, economic, and ceremonial center of the San Juan Basin. Its sphere of influence was extensive. Roads to more than 150 great houses built throughout the region connected dozens of great houses in Chaco Canyon. Current thought is that the great houses were not traditional farming villages occupied by large populations. They may instead have been impressive examples of "public architecture" that were used only periodically during times of ceremony, commerce, and trading when temporary populations arrived in the canyon for these events.

Why the need, for social complexity and integration on such a large scale? Chaco was the hub of an extensive trading network. Turquoise was made into beads, ornaments, and jewelry at Chaco, and traded throughout the Southwest and northern Mexico for parrots, macaws, copper bells, and other precious commodities. Chaco may have been a distribution center for food and resources in response to the region's highly variable climate and growing populations. Ceremonies may have brought "pilgrims" to Chaco along a ritually used road system that connected Chaco to distant communities and to the sacred landscape. We may never fully understand the Chaco story.