Above the entrance to the mine, the darkened, dried blood of sacrificed llamas justified the screams of those awaiting their fate, tethered in the yard nearby. Today was an annual fiesta. I didn't wait to watch. It was minus five at 4,300 metres, and we were about to descend fifty metres inside the mountain to level two, where the temperature would reach plus forty five.

Cerro Rico stands sentinel above Potosí.  It is not only the main source of employment, containing over a hundred mines, it is the town's very symbol and being a National Monument, appears on Bolivian stamps. Rico means 'rich' in both senses, in value and in flavour. Here, 'flavour' should surely be interpreted as the colour of the mineral-filled rock. During its five hundred years of history it yielded silver, then tin, now various minerals including zinc, fool's gold and lead. Now a new seam has been found, and one of the richest. It is known as the 'seam of gringos'. Tourists can descend in small parties, led by the latest cheeky descendant of generations of miners. He calls himself the last Inca - 'AtaEduardo'

Before stooping to pass through the bloodied entrance, we bought dynamite, fuses, coca leaves, alcohol and cigarettes from market stalls as gifts for the miners. We sprinkled some of the alcohol onto the ground for Pachamama the earth goddess, and over a new truck, so that it would function well. After donning sturdy wellingtons, a long plastic coat and a helmet, we were issued with a calcium and carbide water lamp.   For the next twenty minutes we scrambled, slid, crawled and climbed down the rock face, or waded through mud. The tunnels are very low, very narrow and very steep. Sometimes we had to jump down vertical three metre drops. I wondered how we would ever get out. Breathing sulphur fumes and dust, we watched as the workers prepared dynamite and fuses.

Despite an assurance that they would not use dynamite whilst visitors were down there, we heard eight explosions.  After each one my knees were jelly. Suddenly a cart rushed along the track, laden with rocks, and we had to get out of the way pronto, pressing ourselves against the face. I watched, by torchlight, as sacks were winched up from a vertical shaft, when a grimy face appeared a few centimetres from mine, and a dry voice cracked 'agua, agua!' I gave him my water bottle expecting him to take a swig, and he downed the lot in seconds, muttering thanks as he disappeared back down into the darkness. Over three hundred and fifty miners work on level three, some twenty five metres below us.

Tiny blackened boys ran along pushing wheelbarrows. Until recently they would have been running along carrying sacks. At the end of one tunnel was a shrine to the devil. God is for the sky, the daylight. Down here you worship the master of darkness. The effigy was surrounded by gifts of booze bottles and cigarettes. He wears wellington boots, is endowed with an enormous penis, and from his bulbous face, with huge bulging eyes, hang numerous party streamers.

When we emerged we were as black as the miners, caked in sweat and dust. The sulphur fumes were to stay with me for days.

After a lunch of quinoa soup, llama meat and huge corn eyes, we drove out of town to bathe in the thermal lake at Terrapaya. AtaEduardo dressed up in a skirt made from shredded newspaper, caked himself in grey volcanic mud and danced for us, as his sidekick Tanquecito, dressed in black patent winklepickers, placed traditional potatoes, sweet potatoes and yucca underground, to bake among stones heated from a fire. He cooked sausages on a makeshift barbecue using no implements, turning the meat with his fingers. Later, we too had to lift our portion off the fire and use our fingers to eat.

Refreshed, we took to the road again. Rounding 'Devil's Bend', panpipe music haunted us from the minibus radio. Cerro Rico loomed ahead, glowing red and gold in the sunset, overlooking and protecting the livelihood of the town