From Zurich: It is a two train trip to which you can set your watch to through tunnels, bridges and beautiful gorges which run along the glaciers to Saint Moritz. (“Unesco” recently marked parts of the 3 1/2-hour ride as a World Heritage Site, honoring the rail’s amazing mountainview design).
From here, trains depart every 30 minutes to Samedan which takes 12 minutes. (In high summer, ensure your share of Alpine breezes in an open-air Aussichtwagons)
From Milan: The entire route takes about 2 hours and 30 minutes with the Bernina Railway “Red Train”.