In 1606 Prince Archbishop Wolf Dietrich von Raitenau had a palace built outside the town walls for Salome Alt which he called "Altenau". Salome Alt was the daughter of the prominent merchant and councillor, Wilhelm Alt, and the prince archbishop´s mistress. She bore him 15 children, of which 10 survived. Salome Alt had no political significance.
After Wolf Dietrich´s death - he was forced to abdicate in 1612 and was held captive in the Fortress until his death - Altenau was re-named "Mirabell" by his successor, Markus Sittikus von Hohenems (1612 - 1619). Prince Archbishop Paris Lodron (1619 - 1653) included the palace and gardens in his extended ring of fortifications. He spent much of his leisure time at Mirabell which he loved and where he died on December 15, 1653.
Prince Archbishop Franz Anton von Harrach had the palace remodeled extensively from 1721 to 1727 by the famous Baroque architect, Lukas von Hildebrandt, who combined the individual parts of the building to form a homogeneous palace. The palace was heavily damaged by the disastrous town fire on April 30, 1818, destroying the frescoes painted by Johann Michael Rottmayr and Gaetano Fanti. Fortunately, the great marble staircase leading into the palace and the Marble Hall remained undamaged.
Peter de Nobile, court architect and director of the school of architecture in Vienna, gave the palace its present unassuming, neo-classical appearance. Details such as the scroll work around the windows, the chapiters and the stucco work are the reminders of its former splendor. The stairway by Lukas von Hildebrandt is one of the palace´s great masterpieces. White marble putti (cherubs) adorn the lavishly embellished marble balustrade; the figures in the niches are the work of the famous sculptor, Georg Raphael Donner (1726) and among the most beautiful creations of the European Baroque era.
Today the Marble Hall, formerly the prince archbishop´s banquet hall where Mozart´s father Leopold and his children Wolfgang and Nannerl once played their instruments, is acknowledged to be one of the "most beautiful wedding halls in the world". The Marble Hall also serves as an elegant venue for conferences, awards ceremonies and exquisite concerts (Salzburg Palace Concerts).
Famous personalities have stayed at Mirabell Palace: three years before the great fire on July 1, 1815, just after Salzburg was transferred to Bavaria, Prince Otto of Bavaria, later to become the King of Greece, was born in Mirabell Palace.
One year later Salzburg became "Austrian" again and Mirabell Palace became the summer residence of the emperor. Archbishop Cardinal Maximilian Josef von Tarnóczy lived in the palace for 12 years, from 1851 to 1863. The legendary Capuchin monk, Joachim Haspinger, loyal companion and comrade in arms of the Tyrolese patriot, Andreas Hofer, was a guest of the emperor from September 4, 1854 to January 12, 1858 at Mirabell Palace, where he died; a commemorative plaque was placed in the palace courtyard.
Today the Palace accommodates the office of Salzburg´s Bürgermeister (mayor) and the municipal administration.