The word _pueblo_ in Spanish means simply “town;” but in American ethnography it has obtained a special signification from the aboriginal structures so-called, whose remains are found in profusion in Arizona and the neighboring localities over an area about 350 miles from east to west and 300 miles from north to south.[129] These are buildings several stories in height, either of stone or of adobes, communal in character, that is, intended to accommodate a whole gens or clan, and usually with certain peculiarities of finish and plan. The adobes are generally large, some four feet long by two feet wide, and were often made upon the wall itself, the clay or gravel being carried in a moist state in baskets of this size and deposited upon the wall till the mass dried. When stones are employed, they are held together by a mud mortar. The most celebrated of these adobe edifices are perhaps the Casas Grandes in the valley of the San Miguel river, in northern Chihuahua. They have frequently been described and do not differ except in size from hundreds of other ruins in the Gila basin. In connection with the pueblos stand the “cliff-houses,” structures of stones usually carefully squared and laid in mortar, found in great numbers and over an area of wide extent in the deep gorges or cañons of the Colorado, the Gila and the upper Rio Grande, and their numberless affluents. They are perched upon the ledges of the precipices, which often descend almost perpendicularly for thousands of feet, and access to many of them could have been only by ladders or ropes. Prominent points are frequently surmounted by round or square stone towers, evidently for purposes of observation. The disposition of the cliff houses renders it certain that their plans and positions were selected with a view to make them safe retreats from marauding enemies.