The Greina is one of Switzerland's most beautiful and largest plateaus and one of the few still natural contiguous areas of Switzerland. For this reason, the Greina plain has been included in the Federal Inventory of Landscapes and Natural Monuments of National Importance in Switzerland as a protection zone.
The plain is about six kilometres long, one kilometre wide and is located at 2200 metres above sea level. The Greina pass connects Grisons in the East with the Ticino in the West. The three valleys, Val Lumnezia, Val Sumvitg and Valle di Blenio, are only connected via the Greina plain.