The strada statale 39 is known as the main access road to the Italian Alps from Bergamo, the Lombardy plain and beyond. It leads to Aprica, Tirano and Bormio, and then up, up, up to the summit of the Passo dello Stelvio.
On Tuesday the SS39 will lead to the gates of hell for the 2017 Giro d'Italia and host the queen stage of the race, the so-called 'tappone', the first of five mountain stages before the final time trial to Milan. The fight to try to break Tom Dumoulin's grip on the maglia rosa starts here.
After two weeks of nervous racing, of jabs and body blows, attacks and chases, Dumoulin leads Nairo Quintana by 2:41, with Thibaut Pinot third at 3:21 and Vincenzo Nibali at 3:40. Behind them are a dozen others within 12 minutes of Dumoulin, all fighting for a shot at a podium place or in the top ten.
Dumoulin's lead is significant, but the overall classification is still 'corto' as they say in Italy. It expected to open up significantly after the 222km haul from Rovetta to Bormio.
"I expect a lot of attacks by riders who want to win the Giro d'Italia. I think the gloves will come off," race director Mauro Vegni predicted on Italian television on Sunday, assuring everyone about the conditions of the Stelvio.
The risk of rain and snow has passed. The Stelvio will be closed to non-race vehicles to avoid the small risk of sparking avalanches. The summit of the Stelvio has been cleared of snow in recent weeks and is ready to host arguably the most spectacular stage of this year's Giro d'Italia.
"Conditions are fine but we're monitoring things closely to ensure everyone's safety," Vegni said. "I think the Stelvio will see three or four riders emerge to fight for a prestigious stage victory and the overall classification."
Former professional rider and now Cannondale-Drapac directeur sportif Charly Wegelius knows the Stelvio well. He was in the team car when Ryder Hesjedal set up his 2012 overall victory with a determined ride to the summit. He was also present when Nairo Quintana and Hesjedal attacked on the descent in the snow in 2014.
"Dumoulin has shown that he's got exceptional condition but he's only shown it on one-off climbs that are in his favour. But these final stages – and especially the Stelvio stage – will be a different kettle of fish," Wegelius warned Cyclingnews.
"Quintana, Nibali and the others will have to ride an aggressive race and not wait until the last climb as if often the usual tendency. To break someone like Dumoulin, you've got to go early and risk showing their hand."
Nairo Quintana, Pierre Rolland and Ryder Hesjedal emerged from the snow on the Stelvio to sun in the valley - Photo Sirotti
Il doppio Stelvio
The double climb of the Stelvio offers the perfect stage for a heroic attack, something that will make the 100th edition of the Corsa Rosa special.
The 222km stage starts in Rovetta near Paolo Savoldelli's home in Clusone high up the Val Seriana. The first 60km will be fast and furious as riders try to get in the break of the day. Whoever makes it will need strong legs and a will of steel.
The stage includes the easier but still steep Monno side of the Mortirolo after 60km but it is only an antipasto to the main meal of the double Stelvio whopper.
The riders will pass through Bormio after 122km leaving 100km of racing. The climb to the summit from Bormio is 21.7km long, with an average and largely constant gradient of 7.1%. The Stelvio tops out at 2758m and is this year's highest climb, where the first rider across wins the Cima Coppi prize.
The first 'passaggio' of the Stelvio is followed by the descent of the legendary Trafoi hairpins down to the intermediate sprint in Glorenza, back at an altitude of just 917m. The peloton will face 40 hairpins during the climb and then 48 more on the descent that cuts and curves into the side of the legendary mountain.
The stage loops around into Switzerland for the 13.4km Umbrialpass that joins the Stelvio two kilometres below the summit. The Umbrialpass is 13.4km long and climbs at a steeper 8.4%. This is where the important attacks are expected.
After a total of 5300 metres of climbing, the stage concludes with the dizzying 20km descent to the finish in Bormio. It could see attacks pulled back but could also inspire others attacks. The Stelvio stage will entertain right to the very end.
Previous winners in Bormio after similar stages in include Fausto Coppi, Charly Gaul, Erik Breukink, Gilberto Simoni and Damiano Cunego. That is an exclusive club well worth joining.