Vienna has a population of 1.7 million people and was formerly the seat of power for the Hapsburg and Austro-Hungarian Empires. Some of Vienna's most famous attractions include the Riesenrad ferris wheel, the Danube River, Prater Park, Stephansdom Church, the Hofburg Imperial Palace, the Spanish Riding School, and Schonbrunn Palace and Vienna Zoo. Vienna is also known for waltz music perfected by the Strauss family and opulent 19th century balls that still occur today.