Gandersheim Abbey is the reason Bad Gandersheim matters. The former imperial house of canonesses was founded in 852 by Liudolf of Saxony and Oda, whose family would become the Ottonian dynasty. Its present church is a Romanesque basilica with later Gothic work, a broad west front, and the sort of plain mass that makes small German towns suddenly feel very old.
Hrotsvitha of Gandersheim wrote here in the 10th century. Her Latin dramas, poems, and imperial history give the church a literary importance that is easy to miss if you only look at the stonework.