Take a breather from your hectic day and enjoy a change of pace at Cathedral of Santa Maria. Take a quick look inside or stay longer for a mass.
You're spoiled for sightseeing choice in Calahorra. Cathedral of Santa Maria is a good place to begin here, but there are loads of other worthwhile attractions to check out. Tierra Rapaz, Fungiturismo, and Museo de la Verdura are not far from the principal church and will fill in your day nicely.