As befits a service connecting two of the most glamorous resorts in the Alps, Zermatt and St Moritz, the Glacier Express is the last word in panoramic luxury. It needs to be, because in just eight hours it traverses the heart of Switzerland's highest mountain ranges. The journey starts at the foot of the twisted pyramid of the Matterhorn and skirts the Bernese Oberland, following the valley floors (in summer, riotous profusions of wild flowers) where the Rhône and the Rhine begin, and just below the line where glaciers spill out from the high passes.
The landscape is a roll call of iconic names. The snow-capped surrunits of Sehilthorn, Jungfrau, Monch and Eiger pass in distant backdrop, and the high peaks close in around the climbing train. Soaring viaducts arch above cloud-filled chasms, carrying it up and over the 2,033 m (6,668 ft) Oberalp Pass. Edging round sheer precipices, across 291 bridges and through 91 tunnels, the Glacier Express brings you so close to the mountains you can actually see the occasional chamois looking outraged at having to share the elemental magnificence of its rocky perch.
In fact, the train is every bit as first-class as the scenery. Though it has both 1st and 2nd class seating, everyone sits (in great comfort) beneath a glass roof, with good services at their disposal. The difference is that 2nd class is more crowded, an indicator of the train's popularity throughout the year. In summer it provides access to some of the finest high alpine walks; in winter it serves three of Switzerland's most justly celebrated skiing areas. But most people take the Glacier Express for the sheer joy of sightseeing in luxury - and then high-stepping off the train in the unadulterated chic of St Moritz or Zermatt.
WHEN TO GO
Year-round. Seat reservations are mandatory and lunch on the train should be pre-booked.
TIME IT TAKES
About eight hours (Zermatt to St Moritz, via Visp, Brig, Andermatt and Churl. The unhurried pace of the ascents and descents justifies the route's nickname of 'the Slowest Express Train in the World'.
The tunnel at Furka - with its viaduct approaches and staggering ravine views, both a technological and scenic triumph.
The view from the top of the Oberalp Pass, looking along the length of the Alps. On a really clear day you see some 50 peaks in serried ranks leading to Mont Blanc.
The descent from Chur (Switzerland's historic and oldest township) to St Moritz.
YOU SHOULD KNOW
The Glacier Express also has a 'Premium' service available for private parties of a single carriage or even whole trains.