The Mönchsberg, at 507 meters (1,663 ft) above sea level, is one of the five mountains in the city of Salzburg, Salzburgerland, Austria. It is named after the Benedictine monks of St Peter's Abbey at the northern foot of the mountain.
The Mönchsberg shapes Salzburg's historic townscape with its long drawn back consisting of conglomerate (Nagelfluh). The massif is a solidified river crushed stone, deposed as a delta into the interglacial see (Mindel-Riss Interglacial), which was not cleared away thereafter by the glaciers protected from the hard limestone of the adjacent Festungsberg and so remained.
Water ingressing into numerous bursts and cleavages can lead to falling stones and demolition of whole rock sections: In the early morning of 16 July 1669 tons of rock fell off the mountain on the Gstättengasse street below, killing about 230 citizens in their sleep by destroying two churches, a seminary and 13 houses. Since then there is the office of a Bergputzer (mountain inspector), filled by mountaineers who regularly and since 1778 annually dispose loose rocks and prove the condition of the mountain surface to examine. Thus a new disaster could be prevented.
Driven into the walls of rock above of the St Peter's Cemetery, established about 700, are Early Christian hermitages, called Katakomben (catacombs), which however never were funeral places.
Already from 1137 to 1143 the Archbishop of Salzburg had the Stiftsarm branch of the Almkanal built through the mountain, in order to lead the waters into the city. This early adit system can be visited during the annual Almabkehr in September.
The Sigmundstor (colloquially Neutor) city gate, a 131 m (430 ft) long tunnel with elaborate Baroque portals, was built from 1764 to 1766 through the mountain at the behest of Archbishop Sigismund von Schrattenbach; it is today one of the oldest street tunnels in Central Europe. Large air-raid shelters in the mountain were built during World War II. After 1970 some of these were enlarged to an underground car park for more than 1400 vehicles.