https://www.ricksteves.com/europe/austria/salzburg
Of Rick's list we did the following during our winter (February) three days in Salzburg:
▲▲▲ Salzburg's Old Town Walk Old Town's best sights in handy orientation walk.
▲▲ Salzburg Cathedral Glorious, harmonious Baroque main church of Salzburg.
▲▲ Getreidegasse Picturesque old shopping lane with characteristic wrought-iron signs.
▲▲ Hohensalzburg Fortress Imposing castle capping the mountain overlooking town, with tourable grounds, several mini-museums, commanding views, and good evening concerts.
▲▲ The Sound of Music Tour Cheesy but fun tour through the S.O.M. sights of Salzburg and the surrounding Salzkammergut Lake District, by minibus, big bus, or bike. [Panorama Tour 1A]
▲ Mirabell Gardens and Palace Beautiful palace complex with fine views, Salzburg's best concert venue, and Sound of Music memories.
▲ Steingasse Historic cobbled lane with trendy pubs — a tranquil, tourist-free section of old Salzburg.
St. Peter's Cemetery Atmospheric old cemetery with mini-gardens overlooked by cliff face with monks' caves.
St. Peter's Church Romanesque church with Rococo decor.
Dinner at the Old Fox: http://www.alterfuchs.at/de
Mozart Dinner Concert: http://www.stpeter-stiftskeller.at/en/mozart-dinner.html
PS. We didn't buy a Salzburg Card. We walked everywhere except for the funicular to the castle and the SOM tour. We didn't need transit.