It's worth noting, however obvious, that if you book train (or for that matter, bus) tickets through an agent you will inevitably pay more for them than if you buy them directly yourself.

The first town out of Puno towards Cusco is Juliaca , an hour away across a grassy pampa, where it's easy to imagine a straggling column of Spanish cavalry and footmen followed by a thousand Inca warriors - Almagro's fated expedition to Chile in the 1530s. Today, much as it always was, the plain is scattered with tiny isolated communities, many of them with conical kilns, self-sufficient even down to kitchenware.

Passing beyond here through a magnificent glacial landscape, the train pulls up outside Ayavari station (3903m). Once a great Inca centre with a palace, sun temple and well-stocked storehouses, it's now a market town, notable for the women's weird and wonderful hats. You can see an interesting old church from the train - low but with two stone towers and a cupola - and it's a perfect place for trekking if the urge grabs you.

Next stop is La Raya , a scenic pass between the Vilcanota Valley in the Amazon watershed and the Titicaca Basin which flows down into the Pacific. Enclosed by towering mountains, some of them snowcapped, it's the sort of spot that makes you feel like leaving the train and heading for the horizon.