Thanks MikeL2, I think the highlight was the Tren a las Nubes (Train to the Clouds) which left Salta at 7:05am and arrived at the highest point (4,200 mtrs) at 2:40pm. The scenery when climbing the Andes was awesome. For the journey down we all changed seats with the folks sitting opposite so we had different views. The train arrived back in Salta at 11pm, which made it a very long day indeed as we got up at 4:30am!!