The Plaça Major is the heart of Sant Mateu and the reason most visitors come. It is a long, irregular space lined on three sides with stone arcades — porxes — running below the upper-storey façades of the medieval and Renaissance houses that surround it. Several of those houses still have their original Gothic and Renaissance doorways and coats of arms.
The square is at its best in the late afternoon when the low sun catches the arcades and the cafés put their tables out. On Friday morning a small market sets up here, mostly selling local produce and a handful of cured meats and cheeses. From here every other sight in Sant Mateu is a short walk.