But climb it does - just short of a lung-sapping five kilometres (three miles) above sea level, where even the internal combustion engine is forced to toil and splutter. Then it pauses for a while on the snow-flecked crest of the Andes before pitching - like a giant white knuckle ride - into the abyss. The road from Bolivia's main city, La Paz, to a region known as the Yungas was built by Paraguay