The vertical trek that takes your breath away before you've even started

If two-and-a-half weeks on a bus around Peru's lower half teaches you anything it is that this is a country of formidable contrast. Even if time constraints prevent you from visiting the lush Amazon basin in the far north you'll still travel through arid desert, dense forest and towns both scruffy (Puno) and stately (Arequipa), each of which boasts its own highly individual weather. During 19 days, we experienced sun, rain, fog and an awful lot of cold. But for the biggest contrast of all you need simply arrive in Lima then fly an hour east to Cuzco. If Lima is so devoid of attraction that it ought to be ashamed of itself, then Cuzco is its polar opposite.

If two-and-a-half weeks on a bus around Peru's lower half teaches you anything it is that this is a country of formidable contrast. Even if time constraints prevent you from visiting the lush Amazon basin in the far north you'll still travel through arid desert, dense forest and towns both scruffy (Puno) and stately (Arequipa), each of which boasts its own highly individual weather. During 19 days, we experienced sun, rain, fog and an awful lot of cold. But for the biggest contrast of all you need simply arrive in Lima then fly an hour east to Cuzco. If Lima is so devoid of attraction that it ought to be ashamed of itself, then Cuzco is its polar opposite.

As you approach by air Cuzco looks as resplendent as it does tiny, a small town the colour of terracotta that nestles tidily in the lap of the Andes. By the time you have been deposited by taxi into its main square, the Plaza de Armas, you are completely won over. We arrived early, before 8am, and headed straight for a breakfast of café con leche and croissants. From the window of the restaurant's second-floor balcony, the vista - cathedrals, churches, cobblestone streets and weaving walkways - seemed almost ridiculously pretty, like a faked picture postcard. We were in the most enchanting city this side of Venice and we were duly in awe.

People head to Cuzco because it is the gateway to the spectacular ruins of Machu Picchu, the abandoned 15th-century Incan city which lies four hours away by train or, if you're foolish, a rigorous three-and-a-half day trek through vertiginous mountain passes. We decided to be foolish. According to the BBC's recent programme 50 Things To See Before You Die, Machu Picchu ranks at number 11. This means that Cuzco throbs with tourism all year round and is overrun with tacky souvenir shops, budget restaurants and, tragically, "authentic" Irish pubs. Yet, despite this, the city clings on to its sense of history and identity, and remains inordinately proud of itself.

Cuzco, at more than 3,000 metres above sea level, is also one of the few cities on earth that, almost literally, takes your breath away. Despite warnings to take it easy on arrival (you need 48 hours to acclimatise), we spent the morning exploring the cathedral and the Santa Catalina convent then wandered through the labyrinthine streets and twisting alleyways. By noon we were paying for our stupidity, doubled over with exhaustion and gasping.

After a light lunch, we spent the afternoon stocking up on provisions for the Inca Trail. I was still unaware of just how tough it would be - it was just 46 kilometres (27 miles), a stroll in the park. The next morning we were striding through the Andes, enthused by the snow-capped views and Adriel, our guide who also dabbled as a shaman. (This he later illustrated with the aid of a naked flame, the ingestion of alcohol and a bizarre incantation.)

While Adriel's banter helped us through Day One, the increasing altitude put paid to any fun by the following morning. For five hours we climbed and by lunchtime the air at 4,200m had thinned so much that I was reeling with nausea and a hammering headache which stayed with me for the rest of the afternoon and into the night.

However, the Inca Trail is all about strength over adversity and by the time we reached Machu Picchu - which is every bit as astonishing as the guide books suggest - I was feeling like Sir Ranulph Fiennes and Superman combined. The trek was now a receding memory and I was free to boast to whoever would listen.

The trek can exhaust even the fittest but Cuzco knows how to mollycoddle you back to life. We eschewed the cheapo backpacker train into town in favour of the Hiram Bingham line which is run by the Orient-Express Hotels company. This was luxury on a scale of almost epic grandeur with fine food and wine, and staff so discreet that they overlooked the fact that we hadn't showered in four days. This juxtaposition of hardship and luxury made for possibly the most surreal experience of my life.

Once back in Cuzco we checked into the Hotel Monasterio which, as the name suggests, is a converted monastery and one of the most elegant hotels I've ever visited. Our room was pure decadence, but plans to enjoy its overstuffed sofas, satellite TV and room service vanished on sight of the bed, a vast expanse of mattress the size of Belgium. Within minutes we were asleep, somewhere between Bruges and Brussels.

The following night, in a quaint restaurant in Cuzco's arty San Blas quarter, I ordered guinea pig, apparently a Peruvian delicacy, cuy - which looked more like road kill as it arrived stripped of fur and major organs, but otherwise intact. Like everything else you've never tasted before, it was reminiscent of chicken. Afterwards, while using one of the guinea pig's front teeth as a toothpick, we wandered up to the top of San Blas. The city below looked magical. If much of Peru is dusty, chaotic and polluted, Cuzco is a beautiful little enclave whose serenity enraptures you upon arrival then does the very worst thing it can do to a homebound traveller: it tempts you to stay.

GIVE ME THE FACTS

How to get there

Nick Duerden travelled as a guest of KLM (08705 074 074; www.klm.com) which offers return flights from Heathrow to Lima via Amsterdam from £660 return.

Where to stay

A double room at the Hotel Monasterio in Cuzco costs from £176 per night including breakfast through Orient-Express Hotels (020-7960 0500; www.orient-express.com).

The Hiram Bingham train (00 51 84 238 722; www.perurail.com) costs from £225 per person all-inclusive.

Further information

Embassy of Peru (0207-2351917; www.peru.info and www.lata.org).