The geographer Alexander von Humboldt (perhaps apocryphally) thought highly enough of Salzburg to consider it one of the three most beautiful regions on Earth that he'd seen. After visiting Salzburg in the fall of 2003, I'd have to agree the city is very beautifully situated in the Austrian Alps. Salzburg is easy to explore, and, not surprisingly, there are many tours offered for those who want to see sites associated with "The Sound of Music", including the Mirabell Palace and gardens. Alternatively, one can learn about the musical history associated with native son Wolfgang Amadeus Mozart, whose birthplace and residence are both open for tours. As an aside, it was while I was in Salzburg that a new governor was elected in California, and I was amused to hear residents of Salzburg speak so proudly of another native Austrian son who had done well in the world! The Salzburg cathedral and the Petersfriedhof (St. Peter's Cemetery) are other memorable sites in the Old Town, and I highly recommend visiting the Hohensalzburg Fortress above the town, which offers the best views I found of the city and surrounding regions.
Logistics: Salzburg is easy to explore on foot, and the Hohensalzburg Fortress can be reached by either funicular or a walk uphill.