In Vienna the nostalgia for the "good old days" meets modern architecture and pulsating life. There's a lot to see within these limits: from the Gothic St. Stephen's Cathedral to the Imperial Palace, to the Art Nouveau glory of the Secession; from the marvellous Baroque palace of Schönbrunn to the Art History Museum to the contemporary architecture of the Museums Quarter.
You should be sure to visit Vienna's St. Stephen's Cathedral, which marks the center of the city and is also its symbol. The Imperial Palace, where the former living quarters of Emperor Franz Josef and Sisi can be admired is not far away from the cathedral. The nearby final resting place of the Habsburg emperors and family (Kaisergruft) is also well worth visiting.
The Schönbrunn palace, once the residence of the Austrian emperors, is waiting for you. Like the Belvedere palace, Schönbrunn offers an expansive park and in addition a modern zoo. It's well worth a day's excursion.