The Swiss resort of Interlaken, which as its name suggests, sits between two lakes, has a surprisingly oriental hue. The greeny-blue mountain-cupped lakes - Thun and Brienz - on either side are a slice of postcard Switzerland, so primped and pretty that they're almost a cliché. The town itself is unexpectedly busy with people from Japan, China and the Middle East: most are here for the scenery and the chance to get up into a spectacular snowy wonderland at almost all times of year. There's a star-struck element at work here, too, because a lot of Bollywood blockbusters have been filmed in the surrounding mountains, and their legacy is a huge fan club of visitors from the Indian subcontinent.
The key that unlocks that wonderland is a different kind of star attraction: a venerable, spectacularly engineered railway, which is celebrating its 100th anniversary. The route that it travels to the top of Europe leads right up to a ridiculously high station lodged on a ridge - the Jungfraujoch, which at 3,454m is the highest railway station in Europe and among some of the highest peaks in the Alps. For a big proportion of the visitors in Interlaken it presents the opportunity for those who have little experience of snow to get up in the cold white stuff without having to go through all the farrago of strapping skis to their feet.
The railway journey up to the Jungfraujoch can, depending on the time of year, start with T-shirts and balmy sunshine, and end, a couple of hours and over 3,000 metres of climbing later, in sub-zero conditions, with fellow passengers almost unrecognisable under hastily-donned layers of clothes. But you do have to choose your day and your weather conditions to be sure of not wasting your money on a whiteout, and there are bad days when Interlaken remains chock-full of the tourism equivalent of migratory salmon, waiting for conditions to change before they surge upstream.
I was lucky, starting out on a blue-skied autumn day when the foliage was still on the trees. The light was so sparklingly clean it almost squeaked. My journey began in Interlaken with Bob, also known as the Berner Oberland Bahn, a blue-and-cream liveried train which scurried happily up into the steep-walled alpine valley towards Lauterbrunnen, alongside a river the colour of glacier mints, which seemed to be telling tales of its mountainous descent as it tumbled towards the comfort of welcoming lakes. As Bob climbed into a land of sloping meadows peppered with typical alpine timber-built farmhouses like big-hatted cuckoo clocks, the train slowed momentarily to engage a cog in between the tracks to help it up the slope.
There was a lot more of this cog-wheel traction to come, because at Lauterbrunnen passengers have to pile out of Bob and into the diminutive old yellow-and-green liveried coaches of the Wengernalpbahn, on the platform next door. Instantly, it felt as if we'd travelled back at least 50 years, and this Lilliputian train rattled arthritically out of the valley bottom as if it was auditioning for a part in a model railway, posing questions in my mind whether it was really up to the job - questions it quickly answered by taking to the mountains like a gazelle.
Now we were into serious climbing territory, as the coaches started to do their slow waltz up through tunnels and cuttings chiselled out of the rock face, ambushing waterfalls and looking down on wheeling birds of prey. After a long stop in the superbly-sited, car-free old resort of Wengen, basking in alpine meadows in the autumn sun, we moved on upwards, swapping the land of flower beds and vegetable patches for deciduous forests, which were to be followed eventually by conifers and then bare rock and the threat of snow.
By now we were seriously high. At the junction of Kleine Scheidegg passengers need to change trains again to the Jungfraubahn, and it's a good moment to stand and gawp at the huge north face of the Eiger mountain, and the next-door Jungfrau, looming above. In summer, the Eiger's face is one of the ultimate challenges for climbers, 69 of whom have died here since 1935 while attempting to conquer it. I decided to take time out to have a coffee on the terrace of the Eigernordwand restaurant and scan the massive wall of rock, feeling a bit anxious in case I should suddenly witness a distant drama, but I couldn't spot anyone making the climb that autumn day.
The next, and final, train is the most daring feat of engineering, and it took me a bit by surprise. If I'd studied the map, I'd have realised that the ruby-red Jungfraubahn effectively eviscerates the Eiger en route to its final stop, making the most of its last assault from within the mountain. In there, it is protected from the horrendous weather conditions that would hinder its journey if it tried to travel on the outside, and is one of the reasons why it can continue to run all year round.
Quite apart from the sheer endeavour of driving an eight-kilometre tunnel upwards through dense rock, the startling thing about this piece of engineering is both how ancient it is - the work was started back in the late 19th century - and what a risky concept it was, to run a train so high, at such great cost, in the hope that tourists might be tempted on board. The Swiss are normally such serious people, it is hard to think what got into them 100 years ago. Banking, yes; cuckoo clocks, a bit of harmless fun; but running trains through mountains, just because someone might want to go and take a look? Surely everyone knew that trains were allergic to anything vaguely uphill. It was a completely nutty idea.
Of course, it doesn't seem nearly so nutty when the Jungfraubahn hums away from Kleine Scheidegg, eats up the slopes and burrows into the dark. You get two stops on this last stage of the journey, at Eigerwand and Eismeer. Both are opportunities to clamber out and walk to big ice-surrounded picture windows cut in the mountain's skin to enable passengers to look out over the giddy heights that Eiger climbers have to deal with every inch of the way, and watch icicles break off and spiral their way down into the void. It's vertigo-inducing stuff.
And then, at last, we rumbled into the Jungfraujoch, a station in a cavern inside the mountain, from where passengers emerge into a complex of restaurants and shops bolted on to the side of the ridge, 3,500 metres above sea level. The view from here is predominantly of a high-altitude, glacier-edged valley, with no sign of vegetation or habitation, so it feels like you've reached a settlement on the moon. And contributing to that feeling of having emerged onto a different planet is the thinness of the air, meaning that you get seriously out of breath just by climbing a couple of steps.
Besides the inevitable watch shop (this is Switzerland, after all) there are three restaurants up here, including the Bollywood, which must be the highest Indian restaurant in Europe, if not the world. There's an Ice Palace with ice carvings, and next year there will be a new attraction, with the opening in April of a moving walkway through a variety of exhibitions.
But the one thing that everyone who comes up here will be sure to do is to emerge into the open air onto the Ice Plateau right on the top. Here ludicrously trussed up figures slip and slide on the snow, start giggling snowball fights, and take photos of each other against a panorama of peaks that has to be seen to be believed. "I can't see the ocean," said a young Indian boy, gazing out over the clouds. You couldn't blame him for complaining; it does seem like you can see halfway round the world.
After that, the return journey seemed a bit of an anti-climax. Once the train emerged from the mountain, I got out at Eigergletscher station to walk down the Eiger Mountain Trail, a well-maintained section of path that keeps close to the railway, for the 30-minute walk down to Kleine Scheidegg. It feels like a proper alpine hike, and an old chapel en route has been converted to accommodate a rather startling memorial exhibition for all the Eiger climbers who have died, with frayed rope ends and dangling boots.
At Kleine Scheidegg I took the alternative route back down via the cheery resort of Grindelwald (rather than Wengen and Lauterbrunnen) and there decided to stop, to find somewhere to stay and to do some mountain biking while the weather was good. So I waved the train away, laden as it was with its now-sleepy international cross-section of visitors returning to Interlaken, where they would eat, Skype and download their pictures. That's what I intended to do, too.