The most striking feature of this structure [ruin] is the round room, which occurs about the middle of the ruin and inside of a large rectangular apartment.... Its walls are not high and not entirely regular, and the inside is curiously fashioned with offsets and box-like projections. It is plastered smoothly and bears considerable evidence of having been used, although I observed no traces of tire. The entrance to this chamber is rather extraordinary, and further attests the peculiar importance attached to it by the builders and their evident desire to secure it from all possibility of intrusion. A walled and covered passageway of solid masonry, 10 feet of which is still intact, leads from an outer chamber through the small intervening apartments into the circular one. It is possible that this originally extended to the outer wall and was entered from the outside. If so, the person desiring to visit the estufa [kiva] would have to enter an aperture about 22 inches high by 30 wide and crawl in the most abject manner possible through a tube-like passageway nearly 20 feet in length. My first impression was that this peculiarly constructed doorway was a precaution against enemies and that it was probably the only means of entrance to the interior of the house, but I am now inclined to think this hardly probable, and conclude that it was rather designed to render a sacred chamber as free as possible from profane intrusion.[23] [Footnote 23: 10th Ann. Rept. U.S. Geol. and Geog. Survey of the Territories, F. V. Hayden in charge (Washington, 1878); report on the "Ancient ruins of Southwestern Colorado," by W. H. Holmes; p. 395, pl. xxxvii.] In this example the tunnel was much larger than usual and the vertical shaft, if there were one, has been so much broken down that it is no longer distinguishable. Nordenskioeld mentions a considerable number of kivas with this attachment, and one which is described and figured is said to be a type of all the kivas in that region, but an inspection of his ground plans shows more kivas without this feature than with it. In his description of a small ruin in Cliff canyon he speaks of--