Peru has a very limited train network, but the lines that do exist offer a great alternative to domestic flights and long-distance buses. Tourists can travel with PeruRail throughout the year, but the wet season can bring mudslides that may shut down services. Due to this problem, Ferrocarril Central Andino offers services exclusively during the dry season. The best season for train travel in the highlands is May to August, when the weather is at its most pleasant. Just keep in mind that luggage theft is a common problem on Peruvian trains — keep all your valuables on your person or stow them as near as possible.
Photo credit: Brian Snelson via Flickr