Salzburg is the fourth-largest city in Austria with a population of around 150,000 inhabitants. The city is located on the banks of the Salzach River, at the northern boundary of the Alps. The climate of Salzburg is cool and humid. Salzburg was the birthplace of famous 18th-century composer Wolfgang Amadeus Mozart. Salzburg is a famous place for tourist because it has many famous landmarks which are mostly located it the Old Town. The entire Old Town of Salzburg was nominated as a World Heritage Site in 1996 with many churches built in baroque architecture style. The Hohensalzburg Castle is one of the largest castles in Europe. Other sights in the Old Town are the Franziskanerchurch, the Salzburg Cathedral, the St Peter's Abbey with the Petersfriedhof, the Residenz Palace, the Nonnberg Abbey, Mozart's birthplace and residence, the University Church, the Siegmundstor and the Getreidegasse. Outside the Inner Old Town are located the Palace of Mirabell with its wide gardens full of flowers, St. Sebastian's cemetery, the palace of Leopoldskron, Hellbrunn with its parks and castles. Landmarks located around the Salzburg area are the Anif Castle, the Schloss Klessheim Palace, the Berghof, the Salzkammergut, the Untersberg mountain, the Basilika Maria Plain on the Calvary Hill, the Salzburger Freilichtmuseum Großgmain - an open-air museum. Two famous festivals are held in Salzburg, the Salzburg Festival and the Europrix. City became famous in 1960 when the film The Sound of Music was filmed in Salzburg. The movie was based on the true story of Maria von Trapp, a Salzburg-based nun who took up with an aristocratic family and fled the German Anschluss.