St. Oswald's stands at the eastern end of the Stadtplatz, its tower visible from much of the old town. The current building dates to a reconstruction completed in 1501, though the church's history on this site goes back further. The interior was remodelled in the Baroque style in the 18th century — ornate stucco, a painted ceiling, and side altars loaded with gilded carving, all quite typical of Bavarian Catholic devotion.
The church is closely associated with Pope Benedict XVI (Joseph Ratzinger), who grew up nearby and whose family attended here. After his election in 2005, Traunstein took quiet local pride in its connection to the papacy — a modest museum exhibit in the town marks the link. The church itself is normally open during the day and draws a modest stream of curious visitors alongside the regular parish.