The Parish Church of Barcelos, dedicated to Santa María Mayor, is a monument that maintains its medieval robustness in its appearance, embellished by decorative and architectural elements that reveal the imposition of the Gothic style on a Romanesque structure. Its construction began in the second half of the 14th century on the initiative of D. Pedro, III Count of Barcelos, whose arms are engraved on the archivolts of the main doorway.

In the interior, the historic Romanesque capitals affirm the medieval atmosphere, contrasting with the tile panels of 1721, which present scenes from the life of Our Lady. In the various side chapels, the baroque decoration stands out, particularly the gilded altars. In the main chapel are preserved some mannerist paintings depicting the Annunciation and the Adoration of the Shepherds. The church is one of the best examples of Romanesque architecture in the north of the country and underwent important transformations from the 15th to the 18th centuries. In the 20th century the rose window was restored and on the south side of the facade there is a bell tower dating from the 18th century. It has been classified as a National Monument since 1927.