Le Dompeter is the oldest church in Alsace, and the Saint-Ulrich chapel is one of the few churches with a tetraconch (quatrefoil) plan.
Church and chapel are around 850m apart, so allow 11 minutes for the group to get there, as access and parking for a large bus is not possible.
It's also best to schedule this visit in the morning or from 4pm on weekdays.