_Cuenca_, one of the most thinly populated as well as one of the most mountainous provinces of Spain, stretches on two sides of the chief watershed, and the waters of the streams which rise in this province from different slopes of the Cerro de San Felipe flow to the Atlantic and to the Mediterranean. Cuenca (7000), the capital, is still untouched by railway routes, and slumbers on its lofty cliff, and emerged into temporary notoriety by its capture and sack by Alphonso, the brother of Don Carlos, in 1874. _Guadalajara_ (6500), on the Henares, though on the line of railway between Saragossa and Madrid, is scarcely more lively than Cuenca, but it contains the school for military engineers, the most distinguished corps in the Spanish army, and which has never stained its character by political intrigue. The province supports a slightly higher population than that of Cuenca. OLD CASTILE was with Leon for several centuries the chief of the rising kingdoms of Spain, and the one into which all the rest gradually merged. It now contains five provinces, _Avila_, _Segovia_, _Soria_, _Logrono_, and _Burgos_. Avila (7000), still surrounded by its mediaeval walls in excellent preservation, is one of the most picturesque cities in Spain, at an altitude of nearly 3500 feet above the sea-level. The province is remarkable as the one in which the rudely-sculptured stone monuments of boars and bulls, the "Toros de Guisando," are chiefly found. They are the art remains of a population whose name, age, and ethnic affinities are totally unknown. The southern half of this province is traversed by the lofty Sierra de Gredos, and hiding in its secluded valleys are some of the most primitive peoples of Spain. There are no other large towns in the province.