Through the Val Leventina to Bellinzona (where it is joined by the MoÃ«sa bringing down the waters of the Val Misocco) enters the lake through a marshy plain at Magadino, about 10 m.
The former, in the 15th century, won the Val Leventina (down which the St Gotthard train now thunders) as well as Bellinzona and the Val Blenio (though the Ossola Valley was held for a time only), while the latter added to the Val Bregaglia (which had been given to the bishop of Coire in 960 by the emperor Otto I.) the valleys of Mesocco and of Poschiavo.
The old town is built on some hills, on the left bank of the Tessin or Ticino river, and a little below the junction of the main Ticino valley (the Val Leventina) with that of Mesocco.
It rises at the foot of the Gries Pass to the west of Airolo; from Airolo to the Lago Maggiore its valley bears the name of Val Leventina, and is followed as far as Bellinzona by the St Gotthard road and railway.