There was a halt, an eager and prolonged lookout over the plain, a scanning of the now distant Indians through field glasses.  Then slowly and sadly the train resumed its march and mounted to the summit of the butte.

Here, in this land of marvels, there was a new marvel.  Incredible as the thing seemed, so incredible that they had not at first believed their eyes, they were at the base of the walls of a fortress.  A confused, general murmur broke forth of “Ruins!  Pueblos!  Casas Grandes!  Casas de Montezuma!”

The architecture, unlike that of Tegua, but similar to that of the ruins of the Gila, was of adobes.  Large cakes of mud, four or five feet long and two feet thick, had been moulded in cases, dried in the sun, and laid in regular courses to the height of twenty feet.  Centuries (perhaps) of exposure to weather had so cracked, guttered, and gnawed this destructible material, that at a distance the pile looked not unlike the natural monuments which fire and water have builded in this enchanted land, and had therefore not been recognized by the travellers as human handiwork.

What they now saw was a rampart which ran along the brow of the bluff for several hundred yards.  Originally twenty feet high, it had been so fissured by the rains and crumbled by the winds, that it resembled a series of peaks united here and there in a plane surface.  Some of the gaps reached nearly to the ground, and through these it could be seen that the wall was five feet across, a single adobe forming the entire thickness.  All along the base the dampness of the earth had eaten away the clay, so that in many places the structure was tottering to its fall.

Filing to the left a few yards, the emigrants found a deep fissure through which the animals stumbled one by one over mounds of crumbled adobes.  Thurstane, entering last, looked around him in wonder.  He was inside a quadrilateral enclosure, apparently four hundred yards in length by two hundred and fifty in breadth, the walls throughout being the same mass of adobe work, fissured, jagged, gray, solemn, and in their utter solitariness sublime.

But this was not the whole ruin; the fortress had a citadel.  In one corner of the enclosure stood a tower-like structure, forty-five or fifty feet square and thirty in altitude, surmounted on its outer angle by a smaller tower, also four-sided, which rose some twelve or fourteen feet higher.  It was not isolated, but built into an angle of the outer rampart, so as to form with it one solid mass of fortification.  The material was adobe; but, unlike the other ruins, it was in good condition; some species of roofing had preserved the walls from guttering; not a crevice deformed their gray, blank, dreary faces.

Instinctively and without need of command the emigrants had pushed on toward this edifice.  It was to be their fortress; in it and around it they must fight for life against the Apaches; here, where a nameless people had perished, they must conquer or perish also.  Thurstane posted Kelly and one of the Mexicans on the exterior wall to watch the movements of the savage horde in the plain below.  Then he followed the others to the deserted citadel.