The Tui Diocesan Cathedral Museum is situated inside the Romanesque and Gothic Cathedral of Tui. The museum occupies the space of the Santa Catarina Chapel. It is composed of pieces from the Cathedral Treasure, like goblets, processional sceptres or sacred ornaments. Some of the most impressive elements are the seat created in 1602 by the metal smith Juan de Nápoles Mudarra and a painted wooden image of the Virgin and Child from late 14th century or early 15th century.

The archaeological section is available for visits in the cloister and the chapterhouse. The selection includes pieces from archaeological excavations from the Romanesque choir, medieval sarcophagus, visigothic epitaphs and old Cathedral grilles. From the Torre da Homenaxe (Homenage Tour) there is a great view of the Miño River, the city of Tui and the Portuguese border.