<P> The Andes Mountains form a north - south axis of cultural influences . A long series of cultural development culminated in the expansion of the Inca civilization and Inca Empire in the central Andes during the 15th century . The Incas formed this civilization through imperialistic militarism as well as careful and meticulous governmental management . The government sponsored the construction of aqueducts and roads in addition to preexisting installations . Some of these constructions are still in existence today . </P> <P> Devastated by European diseases to which they had no immunity and civil wars, in 1532 the Incas were defeated by an alliance composed of tens of thousands of allies from nations they had subjugated (e.g. Huancas, Chachapoyas, Cañaris) and a small army of 180 Spaniards led by Francisco Pizarro . One of the few Inca sites the Spanish never found in their conquest was Machu Picchu, which lay hidden on a peak on the eastern edge of the Andes where they descend to the Amazon . The main surviving languages of the Andean peoples are those of the Quechua and Aymara language families . Woodbine Parish and Joseph Barclay Pentland surveyed a large part of the Bolivian Andes from 1826 to 1827 . </P> <P> In modern times, the largest cities in the Andes are Bogotá, Colombia, with a population of about eight million, Santiago, Chile, and Medellin, Colombia . Lima is a coastal city adjacent to the Andes and is the largest city of all Andean countries . It is the seat of the Andean Community of Nations . </P> <P> La Paz, Bolivia's seat of government, is the highest capital city in the world, at an elevation of approximately 3,650 m (11,975 ft). Parts of the La Paz conurbation, including the city of El Alto, extend up to 4,200 m (13,780 ft). </P>

Where are the sierra madre and andes mountains located