Wikipedia: "PeruRail is a railway operator working tourist, freight, and charter services in southern Peru.
The main line between the port of Matarani, Arequipa (Peru's second city), Cuzco and Puno on Lake Titicaca was formerly known as the Ferrocarril del Sur (Peru Southern Railway), and was for a time owned and operated by the ENAFER state company. It is the second highest railway in the world after the Qingzang railway to Tibet.
From Cuzco, PeruRail provides passenger services on the 3 ft (0.91 m) gauge Ferrocarril Santa Ana to Aguas Calientes, delivering tourists for Machu Picchu.
It operates in a 50-50 venture with Orient-Express Hotels and Peruvian partners, namely Lorenzo Sousa Debarbieri"
For more details about the Puno - Cusco railway see here