The fortress chapel is dedicated to St George, and its basic structure dates back to the first construction phase of the castle during the 13th century. It is presumed that the chapel already existed in a different form before construction work began on the castle, and that both the Georgsberg as well as the Georgsburg (the name of Veste Oberhaus until the 14th century) derived their names from it.
Today it forms part of the Inner Bailey on the fortress’s southern side, right next to the Princes' Building, and to the east it adjoins a stairwell that was constructed in the mid-sixteenth century. In the baroque period the tower was given an onion dome. The impressive interior of the chapel features a low ribbed vault decorated with 600-year-old Gothic frescoes. In addition to Christ the Saviour and various patron saints, there is also a fresco cycle dedicated to St George, the patron saint of all knights, based on a legend of 1240. The St George fresco cycle in Passau is one of the finest and most extensive of its kind anywhere in Europe.