Salzburg is the fourth-largest city in Austria and the capital of the federal state of Salzburg. Salzburg's "Old Town" is internationally renowned for its baroque architecture and is one of the best-preserved city centers north of the Alps. It was listed as a UNESCO World Heritage Site in 1997. Salzburg was the birthplace of 18th-century composer Wolfgang Amadeus Mozart. In the mid 20th century, the city was the setting for the musical play and film The Sound of Music.