Illimani (Aymara) is the highest mountain in the Cordillera Real (part of the Cordillera Oriental, a subrange of the Andes) of western Bolivia. It lies just south of La Paz at the eastern edge of the Altiplano. It is the second highest peak in Bolivia, after Nevado Sajama, and the eighteenth highest peak in South America. The snow line lies at about 4,570 metres (15,000 ft) above sea level, and glaciers are found on the northern face at 4,983 m (16,350 ft). The mountain has four main peaks; the highest is the south summit, Nevado Illimani, which is a popular ascent for mountain climbers.
Geologically, Illimani is composed primarily of granodiorite, intruded during the Cenozoic era into the sedimentary rock, which forms the bulk of the Cordillera Real. Illimani is quite visible from the city of La Paz and is its major landmark. The mountain has been the subject of many local songs, most importantly "Illimani", with the following refrain: "¡Illimani, Illimani, sentinela tú eres de La Paz! ¡Illimani, Illimani, patrimonio eres de Bolivia!" ("Illimani, Illimani, you are the sentinel of La Paz! Illimani, Illimani, you are Bolivia's heritage!")
Illimani was first attempted in 1877 by the French explorator Charles Wiener, J. de Grumkow, and J. C. Ocampo. They failed to reach the main summit, but did reach a southeastern subsummit, on 19 May 1877, Wiener named it the "Pic de Paris", and left a French flag on top of it. In 1898, British climber William Martin Conway and two Swiss guides, A. Maquignaz and L. Pellissier, made the first recorded ascent of the peak, again from the southeast. (They found a piece of Aymara rope at over 6,000 m (20,000 ft), so an earlier ascent cannot be completely discounted.)
The current standard route on the mountain climbs the west ridge of the main summit. It was first climbed in 1940, by the Germans R. Boetcher, F. Fritz, and W. Kühn, and is graded French PD+/AD-. This route usually requires four days, the summit being reached in the morning of the third day.