Tupungato, one of the highest mountains in the Americas, is a massive Andean stratovolcano dating to Pleistocene times. It lies on the border between the Chilean Metropolitan Region (near a major international highway about 80 km (50 mi) east of Santiago) and the Argentine province of Mendoza, about 100 km (62 mi) south of Aconcagua, the highest peak of both the Southern and Western Hemispheres. Immediately to its southwest is the active Tupungatito volcano, which last erupted in 1987.