Trek from Casa Piedra to Plaza Argentina
Aconcagua is the highest mountain in South America and one of the 7 Summits. I have summited twice - 2005 and 2008 via the False Polish Traverse route.
Aconcagua has a mixed reputation as a 'slag heap' and a challenging climb depending on your experience. I found it a fun climb a great way to gain high altitude experience without all the Himalayan hassles.