The town museum occupies a restored Gothic palace just off the Plaça Major and tells the story of Sant Mateu as the medieval capital of the Maestrat — the territory controlled by the Order of Montesa, the Valencian successor to the Knights Templar. The collection is small but well presented across two floors, with explanatory panels in Valencian, Spanish and basic English.
Highlights include a model of medieval Sant Mateu, an exceptional series of Gothic altarpiece panels, and material on Pope Benedict XIII's stay in the town. Allow about 45 minutes; combine with a visit to the church and the Plaça Major on the same circuit. Admission is modest and includes the temporary exhibition space at the back.