This region is found within the municipality of Cadereyta, in the State of Queretaro - one of the craggiest and most picturesque of Mexico. The Sierra of the Doctor runs a length of 25 kms and is 13 kms wide. There is a great difference in altitudes thus enabling one to enjoy a variety of scenery. From the topmost elevation of the sierra, "El Espolón" peak at 3,264 mts above sea level, the view of the river bed of the Moctezuma is spectacular. It is here where one of the largest drops in Mexico is found in what refers to canyons. The minig town of Maconí is located at 1,710 mts above sea leve. This town lies on an arid ravine wherein flows the Maconí river (tributary of the Moctezuma). The mineral resources of the region were exploited ever since pre-Hispanic times, when the indians extracted mercury. Subsequently the Spaniards discovered silver and lead.