Some of these villages were built upon rocky eminences deemed almost inaccessible: witness for instance the ruins of the ancient Pueblo of San Felipe, which may be seen towering upon the very verge of a precipice several hundred feet high, whose base is washed by the swift current of the Rio del Norte. The still existing Pueblo of Acoma also stands upon an isolated mound whose whole area is occupied by the village, being fringed all around by a precipitous ceja or cliff. The inhabitants enter the village by means of ladders, and by steps cut into the solid rock upon which it is based.