Rent a car (4WD not necessary but be absolutely sure your spare tire is fit for service) and drive the incredibly scenic and rugged road through Villavicencio and over the "pre-cordillera" to the remote town of Uspallata. Continue driving on the nicely paved towards Mt. Aconcagua and stop to admire its incredible rugged beauty. Assuming you don't intend to climb it, walk the...