Considering the Zur Triftsperre in Passau?
A VT member wrote the following comment about visiting Passau:
Not a bad deal! by solituda
The town hall (Rathaus) is definately worth a visit to see the paintings in the Great Assembly Rooms. The vaulted ceilings, stucco work, and the paintings are lovely to see and you can take pictures.
The Small Assembly Room can be viewed as well - but bear in mind that this is where the weddings are performed so it may be hard to get in and see it.
This has to be the best deal of anything in town as the admission is only 1 Euro 50 cents!