The 135-metre tunnel through the Mönchsberg was blasted open between 1764 and 1767 to connect the old town with the suburb of Riedenburg — the first road tunnel of the modern era anywhere in Europe. The grand baroque portal on the city side carries a Latin inscription by Prince-Archbishop Sigismund von Schrattenbach: "Te saxa loquuntur" — "the rocks speak of you."
The tunnel is still in daily use by cars, buses, and pedestrians. Walking through it from Sigmund-Haffner-Gasse into Bürgerspitalplatz takes about three minutes and is unexpectedly atmospheric.