The classical terz guitar originated in the nineteenth century and Giuliani composed some pieces for it. It is smaller than an ordinary guitar: this one has a vibrating string length of 57 centimeters.
The name is a deformation of the French "tierce", since it is tuned three intervals higher (GCFA#DG): what you would get by placing a capo in the third position. By raising the third string one interval lower, you get a lute or vihuela tuning, which was what interested most since you can then play the whole vast repertoire of lute or vihuela directly from the tablatures for those instruments.
This is not a reproduction of earlier guitars but a "modern" version: in particular I've used a fan bracing pattern rather than the traditional "ladder" and the neck is as wide at the nut as a regular guitar. I've also used the same type of bridge as the one I've used for my ukes this year.