Vihuela
Vihuela is a name given to two different guitar-like string instruments: one from 16th century Spain, usually with 12 paired strings, and the other, the Mexican vihuela, from 20th century Mexico with five strings and typically played in Mariachi bands.
Other websites
lutesandguitars.co.uk Stephen Barber & Sandi Harris, lutemakers and researchers
vihuelademano.com Alexander Batov, vihuela maker and researcher
Goldberg magazine: Los dos rinacimintos de la vihuela The twentieth-century resuscitation of the vihuela.
Several photos of Spanish vihuelas can be found among the instrument photos at Wayne Cripps' lute pages.
Pictures
Plucked string instruments