Two special sorts of cliff-dwelling are distinguished by archaeologists;
Some of the most famous of these are the North American cliff-dwellings, particularly among the canyons of the southwest, in Arizona, New Mexico, Utah, Colorado and Chihuahua in Mexico, some of which are still used by Native Americans. There has been considerable discussion as to their antiquity, but modern research finds no definite justification for assigning them to a distinct primitive race, or farther back than the ancestors of the modern Pueblo people. The area in which they occur coincides with that in which other traces of the Pueblo tribes have been found. The niches which were utilized are often of considerable size, occurring in cliffs to a thousand feet in height, and approached by rock steps or log ladders.