Topped by an octagonal tower, Mainz’ immense cathedral, built from deep red sandstone in the 12th century, is quintessentially Romanesque. Its predecessor went through a literal baptism by fire when it burned down in 1009 on the day of its consecration. Over the centuries seven coronations were held here. Sunday hours can vary.
Check its online schedule for classical concerts (adult seated/standing €10/5, child free).