Alto is a high and very remote peak on the border between Chile and Argentina just south of Tupungato. it is also known on the Argentine side as San Juan or Meson de San Juan. Piuquenes and Tupungatito are peaks either side with lesser prominence,. Tupungatito is an active volcano.
Alto is in the centre of this photo, Tupungatito on the left and Piuquenes on the right. From Cerro del Plomo to the northwest.
We have run trips to peaks in this area in the past and can easily do so again. For details of how to climb Alto, Tupungato, Aconcagua etc., please see our guidebooks, which are available in English, Spanish, Polish and French editions, direct from us or from all good bookshops and mountaineering shops.