The Cathédrale Saint-Louis sits at the highest point of the upper town and gives Blois its dominant silhouette from across the Loire. The church is a late Gothic rebuild on much older foundations — Romanesque crypt below, 17th-century nave and tower above. From the outside the proportions are surprisingly tall for the relatively modest town it serves.
Inside, the standout feature is the contemporary stained glass. Jan Dibbets's windows replace the postwar plain glazing and bring sharp colour into the long nave; they're worth seeing on a sunny afternoon. The terrace gardens behind the cathedral give one of the best free views in Blois — down over the slate roofs, the bridge, and the Loire.