The Viola Toeira, named after the third string, the "toeira", is a type of Portuguese viola from the region of Coimbra and, generally speaking, from Beira Litoral.
It descends from small Renaissance violas that become popular in Portugal and Spain. It distinguishes itself from other Portuguese popular violas by having an oval sound hole and five orders of strings arranged in an unusual way.
This was the main instrument of the ensembles who accompanied the festive descants and dances, especially in the feasts of St. John, throughout the rural area of Coimbra. It's considered a profane instrument, of amorous, nostalgic and satirical themes. Before the triumph of the Portuguese guitar, in the last quarter of the 19th century, the viola toeira was still used by students in their serenades and songs.
This Viola Toeira dates from 1870 and was built by António Augusto dos Santos, a luthier from Coimbra, whose children, also luthiers, made a career in Brazil.