We are switchbacking up into the Cantabrian Mountains via craggy gorges, sombre stone villages, quicksilver streams and the occasional mildly alarming landslip when an excitable girlish voice from above announces, "In 10 minutes you will reach your destiny!".
Of course our guide, Melany Serpa, means destination, but her English is charmingly off-kilter at times and her blooper all the more amusing for being broadcast over the PA system. And anyway, we are scheduled to have a rare religious experience so who can say precisely what the immediate future has in store.
Our destiny this bright spring morning is Santo Toribio de Liébana, one of the oldest monasteries in Spain and one of Christendom's holiest sites. The monastery is notable for having what is believed to be the largest and best-preserved remnant of the true cross - that is, the scaffolding on which Jesus was crucified. It is framed in a Gothic reliquary of silver, but there is an open rectangular space at the bottom where the faithful (and even heathens such as myself) can touch the timber directly or, if they prefer, kiss it. It seems extraordinary that a piece of wood that changed the world has survived for 2011 years so I ask another of our guides, the ever-sensible Ana Sutil, whether this can really be a relic of the crucifix. "It is a question of faith," she answers solemnly.
Along with Rome, Jerusalem, Santiago de Compostela and Caravaca de la Cruz, Santo Toribio de Liébana is one of those places that rewards the faithful who make the pilgrimage here with the absolution of all their sins - what's known in ecclesiastical circles as perpetual indulgence. "It doesn't matter what you have done, you go straight to heaven," Sutil explains. I'm guessing she sees the spark of salvation flicker vainly in my eyes because she is quick to qualify the limitations of Catholic grace. "To be a true pilgrim you have to walk here," Sutil says, "or come by bicycle."
Our journey has involved no such hardship. This remarkable place is merely a pit stop on our travels through northern Spain aboard one of Europe's most luxurious trains, El Transcantábrico Gran Lujo. Ordinarily its eight-day itineraries begin in the haute-cuisine capital of San Sebastián and end at Santiago de Compostela, or vice versa, with daily excursions by bus to off-rail attractions such as the Santo Toribio monastery. But our abridged three-day trip takes us from Bilbao to Oviedo - through Basque country, Cantabria and Asturias - to sample the style of Spain's finest train.
We have only a few hours free in Bilbao before we're due at the station. As the awestruck photographer races off to capture the rose-bronze luminescence of Gehry's Guggenheim, I grab the nearest bench and marvel at how much the skyline of the Biscay capital has changed since I last visited four years ago. From a vantage point beside the Nervión River a parade of astonishing architecture unfolds, the highlights being Gehry's titanium wonder, César Pelli's shimmering 41-storey tower and the Deusto University's sleekly functional new library designed by Rafael Moneo, the visionary Spaniard who updated Madrid's treasured Atocha railway station and Prado museum. Architecture so defines this city of some 350,000 that its free tourist map lists more than 40 landmarks and the names of the architects who designed them.
Behind the Beaux Arts façade of Bilbao's La Concordia railway station (architects Severino Achúcarro and Valentín Gorbeña), a skylit iron roof shelters the polished navy and cream livery of our train. First impressions of El Transcantábrico Gran Lujo are very promising. The palace on wheels, freshly rebuilt this year, sports four English Pullman lounge carriages (dating from 1923) at the business end of the train and a reticulated tail of Spanish-designed sleepers bringing up the rear. Everything is shiny and new - this is only the train's third outing post-renovation - but acres of Spanish oak panelling and handmade Belle Époque furnishings lend the interiors an old-world elegance.
In the lounge car, copies of Vanity Fair, Hola! and the International Herald Tribune encourage quiet moments lodged in plump armchairs or sofas inhaling the warm perfume of recently oiled wood. Dining tables in the restaurant car have personal picture windows and are dressed in dense linen and fine silver. A small library in the bar-on-wheels offers titles ranging from Oliver Twist to Selling Hitler, but far more enticing are the bottle of cava chilling on ice and the espresso machine I spy on the counter. Life's essentials, present and accounted for.
At 5pm sharp, staff assemble in front of the train in their gold-trimmed uniforms and black bow-ties. We are introduced to them, welcomed aboard, and told the train will depart promptly in one hour and five minutes. It will arrive in Santander, the port-side capital of neighbouring Cantabria, in three hours' time.
The trek west gives us time to unpack and settle into our mobile accommodation. There are just two suites per carriage (reduced from four before the revamp), which means mine, number 10, is five carriages beyond the lounge. I am not a man known for his broad shoulders but even I must squeeze myself along oh-so-narrow corridors, counting down interconnecting cars until I arrive outside number 10. Being wedged between walls has its benefits - you can't lose your balance so carrying a glass of cava through five carriages of moving train is a doddle.
I am to share the suite with a photographer I've never met before (the joys of travel writing), but he turns out to be an extremely decent chap and good company. So it's only slightly creepy that at night we lie mere inches away from each other on our two-metre-long single beds.
A wardrobe divides sleeping and living areas into compact spaces of origami design where no surface is wasted and many fold open to reveal an array of creature comforts. A caramel leather sofa doubles as suitcase storage and extra bed; there are two flat-screen televisions, a sound system, PC, wireless telephone and mini bar. The bathroom shower cubicle performs double duty as a hydromassage and sauna, though I couldn't find anyone who had worked out how to operate its higher functions. A full range of toiletries and accessories (hair dryer, bath robes) is provided.
Back in the lounge, en route to Santander, the cava is cracked open and served with plates of lollies, a bizarre choice of appetiser that proves to be a rare> misstep in on- and off-board catering arrangements. Most meals are taken at well-chosen restaurants in nearby towns, and eating onboard is limited to breakfasts and, on our final day, a really wonderful lunch of regional specialties from this gastronomically evolved, Basque-accented slice of Spain.
They call this magical corner of the kingdom the Green North. It's easy to see why as we rollick along the rails flanked by bright spring landscapes of forests and farmland, valleys and vineyards. The train windows freeze-frame vignettes of rural life: a field of cows equipped with eight bathtubs, recycled as drinking troughs; a huddle of elderly men on a cobbled street who pause their gossip to admire the passing spectacle of El Transcantábrico; the thrills of a Saturday football match; two children waving furiously from the upstairs window of a stone house beside the tracks.
We arrive in Santander as the last light drains from the sky and a salty breeze peels off the Cantabrian Sea. In keeping with Iberian eating habits, at 9.45pm our trusty bus is waiting to take us to dinner at a good local restaurant, El Serbal, where the omnivorous feast begins with bacalao and pil-pil sauce, progresses to skate with squid and an exceptional oxtail stew paired with quince jelly, and ends with cream-cheese ice-cream and strawberry syrup. Wines are a tempranillo from La Rioja and a sweetish Catalan parellada from Penedès.
It seems odd to ride a bus back to the station and then sleep aboard a parked train. I rather fancy the idea of lying in bed while the train trundles to its next destination, but the Transcantábrico doesn't do nights. A staff member suggests passengers would not sleep if the train was moving. The distances involved aren't huge, either, so if the service operated overnight the journey would be almost finished by sunrise.
We usually take off in the early morning and ride the rails for a few leisurely hours. The dining car seats all guests comfortably and offers an indulgent breakfast menu that ranges from pan a la Catalana (jamón Ibérico on tomato-rubbed toast) to caviar canapés and eggs any way. Juice and good coffee are standard but the louche can also opt to start the day with a cava or a Rioja red.
We explore by bus and on foot in well-choreographed outings. On our first day we step back into prehistory at Santillana del Mar, home to the Altamira cave where Paleolithic rock paintings were discovered in 1879. The cave is now off-limits to visitors, but its interior has been reproduced in a purpose-built museum. Wandering through the reproduction "Neocave" trying to muster enthusiasm for facsimile paintings is a bland experience. Knowing the real, World Heritage-listed cave is only 200 metres away, its entrance shielded by a birch copse and security, adds to the disappointment. The only consolation to the visit is a hilarious video claiming to re-create how life might have looked in prehistoric Altamira, complete with chic deconstructed garments that could have been designed by the Antwerp Six.
In the township proper another museum has an exhibition of torture instruments,which sounds infinitely more interesting, but we don't have time to visit. Instead we take a walking tour through the cobbled streets of Santillana del Mar with their golden sandstone façades, rounded pulpit balconies and iron lacework. Gay geraniums tumble from terrace pots. The oldest buildings date from the 12th century; inside the ancient Romanesque church, alabaster windows cast a golden light over proceedings.
Our adventures continue in Comillas, a former royal resort of ornate palaces and an unsung Gaudí gem. Crowning a hilltop as we enter the town is the former Pontifical University, decorated by Domènech I Montaner (the genius behind Barcelona's Sant Pau hospital) and now a centre of Spanish language study. Back at street level and set in elegant parklands planted with plane and magnolia is the Sobrellano Palace, the vanity project of local man made good Antonio López, aka the Marquis of Comillas, a wealthy industrialist and royal confidant.
Beside the Sobrellano is Gaudí's Caprice, a typically extrovert confection of patterned brick alternating with ceramic sunflowers. It was built in the early 1880s and features a whimsical minaret at the entrance supported by four columns. It's like a gingerbread house come to life.
Comillas is a tremendous surprise, a living museum of Catalan modernism and magnificent villas. The stroll up a hill to the lookout at Santa Lucia, a humble hermitage where local fishermen once prayed for their protection at sea, is punctuated by gasps of wonder at the collaborative beauty of monumental mansions and the postcard sweep of the sparkling Cantabrian Sea. My lasting memory of Comillas will be the last thing I saw of it - Josep Llimona's luminous Exterminating Angel, guarding the cemetery on the road out of town. Just beautiful.
That evening the bus carries us over a 15th-century bridge to reach the fishing village of San Vicente de la Barquera. We arrive at restaurant Annua, perched above an estuary fringed with candy-coloured boats, and are welcomed with glasses of cava and raspberry-coated lollipops filled with foie gras. The scene - already ridiculously picturesque - is lit by a lingering sunset glow and for a few glorious minutes we are cast in gold. It is a memorable prelude to the food of young Arzak- and El Bullí-trained chef Óscar Calleja, whose six-course seaside dégustation includes a brilliant foamy potato emulsion flavoured with white truffle and prawn, serrano ham and thyme oil, and a "Cantabrian forest" of velvety venison, wild mushrooms and dried corn cleverly reconfigured as tree branches.
After such a decadent binge, and a regrettable, impromptu party afterwards in the on-board bar, it is a tonic to spend the next day in the great outdoors. The wisdom of incorporating bus outings into the train schedule is proven beyond doubt as we head into the mountains, mist and clouds still lingering in the limestone décolletage and blurring grand landscapes into soft focus. As we climb high into the Picos de Europa National Park, dense forests give way to grasslands dotted with toffee-coloured cows so photogenic that one cynic suggests the local tourist board must have trucked them in earlier. (We are not the first to fall in love with the cows of Asturias. Sutil tells us a passenger was so smitten with them that he bought one for 500 euros and took it back to the south of Spain.)
When the bus parks beside Lake Enol we stumble out on top of the world into a windswept valley of model cows, a pristine lake and a stone shepherd's hut where a good-natured man pours cider into glasses from a great height (natural carbonation) and introduces us to the local cheese.
The specialty of the Asturian mountains is Cabrales, traditionally made from a blend of cow's, sheep's and goat's milk, wrapped in maple or vine leaves and then left to mature in a cave. It has the grey-tinged, fleshy, mould-riddled look of an exhumed corpse, and a stench to match. Ignoring my perfectly reasonable gag reflexes, I swallow a stinking hunk and am rewarded with a stab of sharp, fungal flavour and a chronic dose of halitosis. Disgustingly delicious. So I have another piece, and another, and some bread and hot sausage, and some more cider and, honestly, I can't recommend this combination highly enough as a hangover cure.
As destinies go - and destinations too, for that matter - it's another indelible moment on the Transcantábrico tour.