Coming from the north by the Julier or Albula hills, this high valley reveals itself as only a few hundred metres deep. From Italy and the Maloja false-hill, at a height of 1 800m, it has the source of the Inn. Lake Sils marks the beginning of the river's course, Switzerland's only Danube tributary. With its resort at St Moritz, the upper Engadine has been a tourist destination for 150 years. The agricultural lower Engadine remained isolated until the 1999 opening of the Vereina tunnel.