There are cities set on steep hill-sides, which we shall enter. Terrace after terrace climb the rocky ribs of arid hills. Houses, interspersed with gardens; communities backed by the soft outlines of distant ranges, seen adown the widening valley; and walls, houses, streets, people, landscape; all are of that distinctive colour and character of the Mexican upland, over-arched by the cloudless azure of its sky. Clustered upon these same steep mineral-bearing hills--and, indeed, they are the _raison d'etre_ of the town at all in that spot--are the great mining places, ancient and modern, which form so important a feature of the life of the country on the Great Plateau. Fabulous wealth of silver has been dug from these everlasting hills. Grim and abandoned mine-mouths, far away like black dots upon the slopes, and strange honeycombed galleries and caverns far beneath the outcropping of the lodes, have vomited rich silver ore for centuries: and the clang of miners' steel and the dropping candle are now, as ever, the accompaniment of labour of these hardy _peones_. The very church, perhaps, is redolent of mining, and was raised by some pious delver in the bowels of the hill whereon it stands--a thank-offering for some great luck of _open sesame_ which his saints afforded him. But we will not linger here; Guanajuato and Zacatecas and Pachuca shall be our theme in another chapter, and the tale of toil and silver which they tell. For the moment the way lies down the Great Plateau, among its intersecting ranges of hills, through the fertile valleys, which alternate with the appalling sun-beat deserts.