Much of European train travel is about efficiency and comfort—punctually leaving and arriving and having a cozy seat or sleeper compartment in which to devour the latest issue of the Economist. But rail travel in the United Kingdom and on the Continent is also about experience: gaping out the window at Alpine glaciers, savoring gourmet cuisine in a restored last-century dining car. Accordingly, our favorite European trains don’t necessarily offer the fastest journeys—just the most memorable. All aboard!