One December day in 1888 Richard and Alfred Wetherill hunted lost cattle on the top of one of the green mesas north and west of the Mancos River. They knew this mesa well. Many a time before had they rounded up their herds and stalked the deer among the thin cedar and pinyon forests. Often, doubtless, in their explorations of the broad Mancos Valley below, they had happened upon ruins of primitive isolated or grouped stone buildings hidden by sage-brush, half buried in rock and sand. No doubt, around their ranch fire, they had often speculated concerning the manner of men that had inhabited these lowly structures so many years before that sometimes aged cedars grew upon the broken walls. But this December day brought the Wetherills the surprise of their uneventful lives. Some of the cattle had wandered far, and the search led to the very brink of a deep and narrow canyon, across which, in a long deep cleft under the overhang of the opposite cliff, they saw what appeared to be a city. Those who have looked upon the stirring spectacle of Cliff Palace from this point can imagine the astonishment of these ranchmen. Whether or not the lost cattle were ever found is not recorded, but we may assume that living on the mesa was not plentiful enough to make the Wetherills forget them in the pleasure of discovering a ruin. But they lost no time in investigating their find, and soon after crossed the canyon and climbed into this prehistoric city. They named it Cliff Palace, most inappropriately, by the way, for it was in fact that most democratic of structures, a community dwelling. Pushing their explorations farther, presently they discovered also a smaller ruin, which they named Spruce Tree House, because a prominent spruce grew in front of it. These are the largest two cliff-dwellings in the Mesa Verde National Park, and, until Doctor J. Walter Fewkes unearthed Sun Temple in 1915, among the most extraordinary prehistoric buildings north of Mexico. There are thousands of prehistoric ruins in our southwest, and many besides those of the Mesa Verde are examples of an aboriginal civilization. Hundreds of canyons tell the story of the ancient cliff-dwellers; and still more numerous are the remains of communal houses built of stone or sun-dried brick under the open sky. These pueblos in the open are either isolated structures like the lesser cliff-dwellings, or are crowded together till they touch walls, as in our modern cities; often they were several stories high, the floors connected by ladders. Sometimes, for protection against the elements, whole villages were built in caves. Pueblos occasionally may be seen from the car-window in New Mexico. The least modified of the prehistoric type which are occupied to-day are the eight villages of the Hopi near the Grand Canyon in Arizona; a suggestive reproduction of a model pueblo, familiar to many thousands who have visited the canyon, stands near the El Tovar Hotel.