Stage 4: Cefalu-Etna (180km)
After three days in Sardinia and a rest day, the peloton hops over to Sicily for the first of four mountaintop finishes, at Mount Etna. While Spanish ace Alberto Contado triumphed here in 2011, via a different approach, all eyes will be on Sicily's favourite cycling son Vincenzo Nibali.
Stage 9: Montenero di Bisaccia-Blockhaus (139km)
Coming just before the race's second rest day, the second mountaintop finish will be in the Abruzzo region, at Blockhaus (1,674 metres altitude). Belgian legend Eddy Merckx won here in 1967.
Stage 10: Foligno-Montefalco (39.2km individual time-trial)
The first of two time-trials takes place in the Umbria region following the second rest day. The pink jersey contenders will ride through the Sagrantino wine-growing region.
Stage 14: Castellania-Oropa (131km)
This stage honours two of Italy's biggest cycling champions in Fausto Coppi and Marco Pantani. Starting in Castellania, the birthplace of five-time winner Coppi, it finishes at Oropa where tragic hero Pantani, wearing the pink jersey, won the stage in 1999.
Stage 16: Rovetta-Bormio (227km)
This stage comes after the race's third rest day, and it is probably just as well. Added to the Mortirolo and Stelvio (2,758 metres altitude) is a third climb, via the Swiss side of the mountain, back up the Stelvio. It heralds the start of the most gruelling week in the race.
Stage 18: Moena-Ortisei (137km)
The stage is short, but don't be fooled: four climbs - Pordoi, Valparola, Gardena and Pinei - in the notoriously steep Dolomites means it is brutal. And there's an uphill finish too.
Stage 20: Pordenone-Asiago (190km)
A day before the race finale, a time-trial to Milan, the peloton has one more day of climbing to complete. They will ease into it on a relatively forgiving first half, but get a kick in the teeth on the way up Monte Grappa, which comes before the final climb to Asiago.
Stage 21: Monza-Milan (28km individual time-trial)
Despite a tough, final week in the mountains, the pink jersey contenders will be mindful of keeping enough in the tank for the final day when victory, or defeat, could be decided in a race against the clock from Monza to Milan.
Original source: Giro d'Italia 2017 - the key stages