Prince-Archbishop Wolf Dietrich von Raitenau had Altenau Palace built in 1606 as a token of his love for Salome Alt. The palace fulfilled its purpose: fifteen children were born of their union, ten of whom survived. 
After Wolf Dietrich's death, the palace was renamed "Mirabell" by his successor, Markus Sitticus von Hohenems. 

The Palace: a precious jewel 
Prince-Archbishop Franz Anton von Harrach had Mirabell Palace redesigned by the famous baroque architect, Lukas von Hildebrandt, from 1721 to 1727, integrating the individual buildings into a self-contained complex. The palace was damaged by the great fire that swept through the city on April 30, 1818. A number of frescoes including those by Johann Michael Rottmayr and Gaetano Fanti fell victim to the flames. The grand marble staircase that led into the palace and the marble hall survived unscathed. 
Mirabell Palace owes its present unassuming appearance to Peter de Nobile, the court's architectural consultant and director of the Vienna School of Architecture. Details such as the edging of the windows, the capitals and stuccowork bear witness to the palace's former splendor. The masterly staircase by Lukas von Hildebrandt is one of the most precious works of art at Mirabell Palace. Charming putti (cherubs) decorate the marble balustrade; the sculptures in the niches are the work of the famous Georg Raphael Donner and among the finest products of the European baroque. 

The Mirabell Gardens 
The famous Mirabell Gardens were redesigned around 1690 under Prince-Archbishop Johann Ernst Graf von Thun to plans by Johann Bernhard Fischer von Erlach and completely remodeled around 1730 by Franz Anton Danreiter. The Pegasus Fountain, a work by Kaspar Gras from Innsbruck, was installed in 1913. The four groups of statues around the fountain were sculpted by Ottavio Mosto (1690) and symbolize the 4 elements: fire, air, earth and water. The Mirabell Gardens were opened to the public by Emperor Franz Joseph in 1854. Today they are a horticultural masterpiece and popular backdrop for photographers.