Scanuppia-Malga Palazzo it’s said to be the steepest hardest long climb on a sealed-surface road in Europe (or the world). It's located in Besenello,a municipality in Trentino in the northern Italian region Trentino-Alto Adige/Südtirol.
The ascent is 7.5 km long. Over this distance the elevation gain is 1.317 meters and the average percentage is 17.6 %. The road includes some steep sections (it’s said to be up to 45%), without market central lines. The road climbs from 198 meter altitude over a concrete road up to 1,515 meter altitude. Subsequently a dirt road is leading a few dozen meters further up to the Malga Palazzo.
The surface of the road is paved. What makes it even more difficult is that much of the concrete surface is not "even". Not that it's "rough" (though in a few spots it is that) - but that it's "wavy", like with very wide "ripples" in its surface. This unevenness is intended to provide better traction when there is snow or ice.
-around 12% for about +120 vertical meters as a "warmup"on the wider asphalt road
-around 24% for about +375 meters in lower section of narrow concrete road.
-around 14% for about +135 meters.
-around 17-19% for about +660 meters