mountain in Argentina. It is commonly regarded as the highest summit in the Western Hemisphere, rising 22,834 feet (6,959 metres) above sea level. Aconcagua lies in the Southern Andes, its peak being in Mendoza province in northwestern Argentina, but its western flanks build up from the coastal lowlands of Chile, just north of Santiago. It is of volcanic origin, but it is not itself an active volcano. The first attempted ascent, made in 1883, failed; the summit was first reached in 1897 by Matthias Zurbriggen.