The Mariñas Museum was opened in 1983 in the old convent of San Domingos (17th and 18th centuries). The collection shares the Address with the local archive and library. The museum is devoted to the great region of Mariñas, covering its historical and etnographic aspects.

The visit starts with a panoramic view of the most important figures in medieval Betanzos, surrounded by the remains of the gothic monastery of San Francisco. Among these remains, it is noteworthy the statue of a Pilgrim Saint James, from 14th century - the oldest representation of Saint James in Galicia. The Roman period is represented by outstanding pieces, such as altars, stars and mills.

The etnographic section of this floor present a series of mock-ups of a cottage and other models introducing the visitor to the world of traditional trades related to wine and bread. The first floor holds the Suit Hall, where the visitor can enjoy a selection of folk garments from all Galicia, along with other clothing from the 18th and 19th centuries' bourgeoisie of Betanzos. Also in this hall, there is a good collection of pieces related to textile, like the tools of a local tailor.

The upper corridor holds various objects connected to the history of Galicia and Betanzos, including flags, busts and the balloon flown every year since 1814. In the same floor, there is a hall dedicated to the Antigas Escolas (Old Schools) and another hall devote to Jimenez Cossío Foundation, with embroideries, laces and fans from 16th to 20th century.

In the north corridor, the ministry hall of Rubens School houses thirteen paintings and several etchings from Antwerp. The visit ends with a showing of the urban evolution of Betanzos, through photographs, drawings and mock-ups.