Cortona Cathedral — formally the Concattedrale di Santa Maria Assunta — sits on a small square at the western edge of the historic centre, on the site of an older Romanesque church. The interior is restrained Renaissance, the layout a single nave with side chapels. Most of the better artworks are now in the Diocesan Museum across the square.
The cathedral is most striking for its location, with views west over the Val di Chiana from the small piazza in front. Worth a 15-minute look in passing on the way down through the old town.