The Chacoans were skilled masons, that these pueblos still stand is a testament to their skills. Over time, their techniques evolved from simple walls one stone thick held together with a generous amount of mud mortar, to this more elegant style found at Pueblo Bonito
There are six sites open to the public that are a very short distance from the loop road, Una Vida, located next to the Visitor Center, Hungo Pavi, Chetro Ketl, Pueblo Bonito, Pueblo del Arroyo, and Casa Rinconada. In addition, there are five other sites accessible by trail: the Pueblo Alto complex, Casa Chiquita, Tsin Kletsin, Peñasco Blanco, and Wijiji.
It is impossible to see them all in a day. Plan on staying several days at the park. The campground is located about a mile from the visitor center. I heard rumors that there are hot showers there now.
Again, I visited this place in 2001, so there are many others that have written more than I have, and have better photos.
The visitor's center is an important place to visit in this monument. There are a number of very subtle pieces of the ruins here. For example, the movie in the visitor's center took some hour and a half to describe all the different solar and lunar alignments that were tracked by the structures in the canyon and sculptures on the rocks around the canyon. Some of these places are not publicly accessible at all, and you can only rely on the photos and movie in the center to show these parts of the monument to you.
As an example, one of the solar clocks and star calendars tracks a star alignment that only happens once every 28 years. This level of intricacy of monitoring the stars with entire planned communities around astronomical locations is quite unique, and would have required decades of very careful study and planning.
However, it should be noted that the Visitor's Center is under reconstruction. There is currently a temporary visitor's center in operation.
Climb the trail that goes up the cliffs overlooking Chaco Canyon. It is totally worth it. You get fantastic views of the ruins.
On the morning of the winter solstice in December, the rays of the rising sun shine through this window and strike the opposite corner of the room behind it.