The largest Pueblo ruin in the part is Puerco Pueblo. It is a very short circuit to walk around on a paved walkway and there are plaques occasionally to explain what you're seeing. Also, if you check the self guided tour you get when you enter the park, you’ll find that a park ranger is there at specific times to do a guided tour. We were lucky enough to catch that. He spoke about how these people survived out here. It really looks desolate. Even though the Puerco River was close by, there was absolutely no water anywhere that I could see. So I mentioned that to the ranger and he said the area was experiencing a drought and that this area was grasslands in the first millennium A.D. He went on to say it may have been a spell like this that drove the inhabitants of Puerco to move on.
At its height, Puerco had close to 100 rooms which were probably each one for a family. There were several communal kivas where the men met to talk or work. But unlike other village sites, there wasn't very much left behind when these folks moved on. That told scientists that it was a planned move. However, in one room an altar slab was found. It is very much like the ones used by the Hopi to this day which has led to the speculation that this ancient tribe may have contributed to the rise of the Hopi tribe.
The people of Puerco were contemporaries of the Anasazi to the north, the Sinagua and Hohokam to the west and the Mogollon to the south. However, this is a relatively late pueblo. Mesa Verde was abandoned while this site was still active. There was a group here is the 1100's A.D. and then again in the 1300s. The fact that it had been inhabited and abandoned in the past seemed to me support for the idea that this site was finally abandoned due to water and climate changes for the worse. NOTE: It is here that you will find the spiral solar calendar mentioned in the Petroglyphs entry.
One other old human habitation is worth a look. It is called the Agate House, because it is build completely with petrified wood. It was built somewhere between 1050 and 1300 A.D. and completely reconstructed in 1934. There was very little trash indicating it wasn't inhabited very long. My speculation was it might have been a "honeymoon" type retreat for newlyweds. But I assure you, that is my own speculation and is based on the dating.
NOTE: There are now over 600 identified sites of human habitation in the Park, some dating to pre-ceramic ages -- around 200 A.D. Most of these remain unknown to the public for their safety and preservation.