The MAAM (Museo de Arqueología de Alta Montaña) is worth visiting in Salta. It is a small, very well documented museum custom built to house the Llullaillaco Children mummies and give a glimpse on Inca culture in the region.
For preservation reasons, only one mummy is in display at any given time.
Lots of artifacts on display, videos on the area and a documentary on the expedition that discovered the mummies. The cute gift shop has a nice variety of handicraft, crafts and art pieces, most locally made.