In the center of the kiva roof was a rectangular opening where a ladder provided access into the room. The base of the ladder usually rested near the firepit. When the Anasazi started a fire in the kiva, smoke rose through the roof hatchway. This created a partial vacuum in the room which drew fresh air down through the chimneylike ventilator shaft. The circulation of fresh air made an efficient ventilation system.
Some people refer to it as a spirit hole.
The Hopi people consider that their ancestors emerged through several previous underground worlds, the entrance to each one of these worlds being an opening called a sipapu. The sipapu is a good example of a feature found not just in prehistoric kivas such as this one. It is also found in modern day kivas and is a belief that some of these people still hold. The Anasazi must have taken great pains to construct such walls so straight and square off the corners so well. The two small openings near the top of this wall were used for ventilation of the rooms that were behind it.