Umbrail Pass (8,205 feet or 2,501 metres at highest point, and the highest paved road in Switzerland).
Straddling the Swiss-Italian border, and linking Giogio di Santa Maria in Val Müstair, at the eastern extremity of Switzerland, with Bormio in the Adda valley, in Italy (on the Italian side, it joins the Stelvio Pass road). The ascent from Giogio di Santa Maria is just over 13 km (8 miles) long, and the descent from the summit to Bormio, down the southern slope, is about 1 km (about half a mile) in length.
The pass is closed between October and May.
Caution: This road is narrow, has rough surfaces in places and lacks guard rails/barriers along some sections, with potential drops into the valley from the road of hundreds of feet/metres, if you get it wrong!
A wonderful, exhilarating drive, but NOT for the faint-hearted!