The sixth stage (Bari-L'Aquila) is remembered as the hardest stage in the history of the Giro, with many riders forced to retire, including the first of the general classification Giuseppe Azzini, who was found the next day resting in a country house.
Tre Cime di Lavaredo, Stage 19. The ascent to Tre Cime is one of the most brutal finishing climbs in cycling, especially after a stage with 5423 meters of altitude gain like this one. The climb is 3,7km long and 12,11% steep with a median altitude of 2077m.