The museum in the Mozart House in St. Gilgen on Lake Wolfgangsee tells the story of the former court and its famous inhabitants. Wolfgang's grandfather worked here as the care court judge of St. Gilgen, his mother was born here and his sister Maria Anna "Nannerl" Mozart moved here after her marriage. The Museum is located at Ischlerstraße 15, A-5340 St. Gilgen.

Today's Mozart House was built in 1720 by Wolfgang Nikolaus Pertl, Mozart's grandfather, and Anna Maria Pertl was born here on December 25 of the same year. After the early death of her father, she moved to Salzburg with her mother and sister.

After many eventful years, Maria Anna "Nannerl" Mozart, Wolfgang's sister, married Johann Baptist von Berchtold zu Sonnenburg, the caretaker of St. Gilgen, in 1784 and gave him three children, although only her son Leopold reached adulthood. She spent 17 years in St. Gilgen in Salzburger Land and moved back to Salzburg after the death of her husband in 1801, where she lived until her death on October 29, 1829.