ALTHOUGH Peru has all the ingredients to be an amazing place, some more delicate travelers (like me) find a wealth of reasons not to go. It came as a relief to learn that, at least, the tourism infrastructure is upgrading. PeruRail, an Orient Express affiliate, just launched train service to Machu Picchu from Cusco, whisking travelers to and from the ancient city in grand, Old World style. Cusco is the oldest continually inhabited city in South America. It’s also 11,000 feet above sea level.