By leaving St Jean-en-Royans, you can't really imagine what you will discover. It is true that up to the Col Gaudissard, the road is nothing unusual, apart from its view over the Royans. But after the following turn, leading to the belvedere hanging onto the cliff, you appreciate the work's dimensions. The road was carved out here (with the end of the work in 1898), not for the view, but to make the forestry activity profitable.
The last section of the road is simply exceptional up to the Col de la Machine where a hotel was built to receive travellers, firstly by horse-drawn carriage, then cars and coaches. You discover 4 kilometres of elaborate vertical, weightless staging! The road was inspired by the existing rocky ledge, with each missing part requiring the cliff to be carved or drilled out. Sometimes the road is swallowed by the rock, sometimes it extends over protruding spurs, accentuating the feeling of height.
Make a stop at the Col de la Machine, to look back over the road. At the bottom of the valley, a jet of silver gushes from the rock, the Cholet, responsible for this 5 kilometre long and 2 kilometre wide indentation.
You can continue along the circuit and go down by the route de l'Arps towards Royans or continue to Lente.