You'll probably spot Saintes Cathedral in the skyline before you actually find this amazing place of worship. Step inside if it's open or just appreciate the facade from outside.
When you've finished up at this principal church in Saintes, why not make your way to Saintes Amphitheatre, Arch of Germanicus, and Saint-Eutrope Church? They're not too far from Saintes Cathedral and also a favorite with many tourists.