The Sigmundstor, generally known as the Neutor, is a tunnel in Salzburg built in the 18th century. 131 metres long, connecting the Altstadt with the Riedenburg quarter, it is the oldest road tunnel in Austria. After the 64-metre Urnerloch in the Gotthard Pass (Switzerland) and the eastern bore of the Ilzdurchbruch in Passau (Bavaria) it is the oldest known road tunnel in Europe. In earlier times it was also one of the city gates of the historic Altstadt. From 1916 to 1940 a tramline ran through it, and since then it has formed part of a route of the trolleybuses in Salzburg.