B is for Bandurria, a plucked chordophone originating in Spain and related to the Mandolin. It is used in Spanish folk music as well as being found in many of the former Spanish colonies.
In Medieval times it was a round-backed instrument with three strings. It then became flat-backed and during the Renaissance period it gained an extra string.
Not content with four strings, it became a ten-stringed instrument, five pairs, during the Baroque period. The modern Bandurria has even more strings, twelve in all, in six pairs.
The strings are tuned in unison pairs, going up in fourths from low G#.